I am sorry to hear this. There are so many perfect lines I could tell you to try and make sense of it all and to reassure you it'll be okay - but I know at a time like this, those are the last things you want to hear, therefore I will limit my reply (sort of).
First of all, don't apologize for posting this and I do care, we are here to support each other. Secondly, you can do a million things throughout your life trying to please other people, and in the end still look at yourself and realize
you're not happy. I understand you love your wife, but self-happiness is at the top of priorities. Those happy feelings you felt prior to this are what matter most.
As per your wife's sister, don't even worry about the comments she made, she has no place or control in your marriage. These people only have power over you because you allow them to get to you (with the exception of your wife) - don't view it as taking sides, view it as their loss if they are not happy with who you truly are.
As for your wife, you need to remember she's also hurting simply due to the depression, so don't assume what she says is what she truly means; it could simply be her emotions at the time coupled with the peer pressure of others. You and your wife are the ONLY ones who need to discuss your marriage/relationship issues, it is not the business of anyone else. Take care of her for now, and have a discussion with her later when she's in a better state of mind and doesn't have the opinion of others to influence her words.
Hang in there, don't give up and worry about you and your wife only! PM me if you need someone to talk to further, and never apologize for sharing your mind and asking for a shoulder