Just read through all this and realize there's still a day or so before the dinner you mentioned, so I wanted to give some advice based on conflict resolution I've done in the past. And based on the fact that honesty and putting the cards on the table may not have the result desired.
Basically, I agree extensively with a lot of what Joanna said earlier. But let me get to that in a bit.
Something to keep in mind is that within our own narratives, it's always extremely easy to see our own perspective in things, and ascribe honor and reason and logic to everything we do. Because with the right point of view, there is a lot of honor in what is happening from both sides. In your case, you are fighting for not only his friendship at this point, but also for the right to keep on interacting with all your other mutual friends. In her case, she may see her actions as the correct way to ensure that her husband's commitment is to his family. And that complicates things in the sense that whatever you do with whatever intention, in her narrative she's still the one who is right.
Yes, admittedly it is clear that a lot of what she has done is extremely wrong, but we don't know why she chose to behave in such a way. Passive aggressiveness sometimes is not necessarily done out of bitchiness, but maybe it could just be fear of confronting a fear or an insecurity in a situation.
Maybe she has particular insecurities from growing up. For all we know she lost someone before due to not having the right "build." Maybe one of her previous relationships or friendships ended because of a friend being preferred over her.
Like for example, I have had many situations in the past where I'm in a committed relationship, and when my partner(s) would travel and make friends, I'd encourage them to have fun and be ok with them meeting people ... then they'd come back and leave me due to having done stuff with someone else and having figured they wanted something different in life. Nothing I can blame them for, since that stuff happens, but it does lead now to the point where any time a lover tells me they'll be away in a different city or country for long and they tell me about hanging out with new people or going to parties, I pretty much go into panic attacks. Anytime someone I love tells me they can't talk to me or be around because they'll be doing something with this other cool person they met, it brings back the scar and destroys me completely. And I'm sure it'll take a lot before I'd be completely secure with a husband wanting to spend time with a female friend and share inside jokes and moments with her and not me. Because even with trust and love, those fears and traumas still exist deeply inside me.
We don't know what fears may control her in such a way. And who knows? Maybe she doesn't know either. Maybe at one point in that past year she saw something in you, or he said something about you, that triggered a fear or insecurity, and that leads her to try and find ways to justify to herself that negative perception of you. It could be why she looks for ways to take jabs at you even if they make no sense. To the point where it seems she finds justification in doing her best to push you away from their life.
Now, back to what Joanna said, I think there is wisdom in trying to change the perspective she may have of you by creating a different image of yourself to her.
Right now, you're the girl who wants to spend time with her husband, and gives him meaningful gifts that could remind her you share bonds with him she can't compete with, and who has looks she can't attain.
I'm afraid that if you bring up the issue with the idea to solve it, that she will instead internalize completely the fact that you really do see this as a competition and are clearly marking your territory. And won't give him up. In short, you could be confirming her fears and insecurities and giving her a solid reason to hate you. Not only that, but it's an issue that can be even more explosive given she is pregnant as well. I'd feel horrible if my husband and future father of my child sided with his female friend and not with me (because given her attitude she's probably going to be seeing this as a competition between two sides.) Can you imagine how that would feel?
And that's the other thing. You're putting your friend in a situation where he is forced to make a decision that will inevitably betray the expectations of one of two people he really cares about. You're putting him in a situation in which he can only lose, because if he agrees with you then he'll be making his pregnant wife into the bad one in the story and hurting her in the process, and if he sides with her after you confront the situation with the adamant desire to keep him ... well, I'm sure you would be hurt too, no?
It's a situation that handled wrong will inevitably hurt someone in some way, potentially everyone since it puts your friendship(s) at risk, puts his friendships at risk, puts her safety of mind at risk, and could potentially put a wedge in their marriage given that it's clear that there's already been moments of him getting angry at her over you. That's waaay too many relationships on the line to risk.
If I were you:
1. I would go with what joanna said: engage her in a way that will make it difficult for her to perceive you as someone to fear. Work at taking away any reason she may have for hating you.
2. I'd use the dinner as an excuse to offer or ask for a moment of just you and her. You know, like offer to go with her one afternoon to shop for baby clothes or a stroller or something to treat her and congratulate her for the baby (since the cigar is the sort of congratulation gift that was just for your friend, it could be nice to acknowledge her part in it too, the fact it's not just your friend having a baby but her too.)
It's also important you interact with her in a context that doesn't force you to compete for your friend's attention or time.
3. Ask her for help or advice with something meaningful. If two people with power clash it's just a mess, but asking for help puts you in a position where it'll be harder for her to see you as a threat or danger, and that could mollify her a bit.
And in the case she's still "bitchy" after being asked for help/a favor/advice, it's harder for her not to look like the jerk of the story. So even if her inclination is to be that way just because, all she can do is back down a bit or look like an awful person.
4. A bit more difficult, but drop a line or a hint somewhere about how you envy or admire something about her, in particular her looks since that seems to be a possible trigger. If it's jealousy about your looks, she'll feel better if she knows you find her to have something you don't have. Even if she hates you, she may take you less seriously as a threat if she has that knowledge and stop being so aggressively against the idea of you.
Of course, this is all very difficult because, by all means, the main desire here from anyone is to want to curse at her extensively, put the foot down, and expose her for the passive aggressive bully she has been. You know, also known and sweet sweet justice.
But putting a scared, insecure bully against a wall will just make them even more defensive and entitled, and no one wants that. So I would really really recommend trying to ease your position a bit and consider her point of view as much as humanly possible, since you are in the position of taking control of the situation and taking the higher road in which everyone's happiness is considered.
I hope I was able to help in some way, even if just to help put forth another perspective of the situation out there.
Best of luck at your dinner Nicole, and I wish you a lot of strength and wisdom to make the right decision in such a difficult situation. Hope everything works out well!
