Here's the situation and I'd like some feedback please.
First off I live full-time as male. All the newer employees know me only as male but there are many who knew me pre-transition. It's been emphasized ad nauseam that pre-transition employees use only male pronouns for me. Many people are doing better, however there are some that haven't been trying at all. It's not like I came out just recently so we've been working on this for awhile know.
We had some outside people come in Monday to do some things for us. I was introduced as male (as should be) and the employees around them strictly used male pronouns. The outside people were in my office, I was interacting with them and they used male pronouns. I stepped out for a bit and when I returned things turned ugly.
When I returned one guy have me the worst look. He had his mouth open and was checking me out up and down. Even though this could be a sign he couldn't believe I was born female it was creepy and rude. After that they started using female pronouns and talked to each other like I wasn't even there.

Despite being corrected they continued to use female pronouns.
Later they went into my manager's office which is connected to mine. My manager wasn't in there while they were doing things to her computer. While in there I heard them making fun of me being trans. They thought I wouldn't hear even though I'm just a few feet away. Dumbasses.

They did try to be quiet but I purposely listened to them. Normally I would've confronted them but I didn't want our working relationship to start out bad since I'll have to see them alot in the future. Plus it might seem weird because if I wasn't trans I wouldn't be trying to eavesdrop as much. I also have no idea how much they were told and really didn't know what to do.
Considering the situation the only thing that could've happened was somebody told them. It may have even been accidental by someone using the wrong pronoun, but something happened. People don't just suddenly assume your trans when others are using the correct pronouns when talking about you.
I don't want to make a big deal about it with the outside people. Mostly because, if I wasn't trans, not a big deal would be made of it. They would simply be corrected next time. My manager and I have put into place ways to resolve this with them next time.
Here's my problem. I asked my manager to send an e-mail to pre-transition employees explaining the situation. I want them to know that as time goes on using the wrong pronouns will cause more problems, confusion and embarrassment on my end. She says she can't believe these outside people would do or say what they did- so basically she deosn't believe me. WTF?! She wasn't even there!

I told her this did happen.
Why would I make something like this up? This is the
last thing I want to happen. She spoke with the general manager about this and he recommended they have a meeting and bring it up.
HELLO?! That would just out me to the employees who don't know! After I brought that up they decided not to do that.
For that last four days this has been discussed several times a day with my manager, the general manager and the owner. I don't want an apology from the outside people. I don't even want to find out which employee outed me- mistake or not. All I want is for people to realize that opening their mouths before thinking can cause problems, confusion, embarrassment and can harm me. We're a very small company so sending an e-mail out would take little time at all.
For being a place who "supports" me, whenever I have problems not much is done. I'm told "it's hard to remember". Bull->-bleeped-<-. Not after all this time, especially since some people aren't trying at all. And yes, maybe it is hard to remember. That doesn't make my embarrassment, harassment and depression any less. It's been four days and so far nothing has been or is planned to be done. I've talked to all the people in charge who have power to do anything. I feel violated and betrayed.
My situation gets even worse though. I don't want to quit my job because then I'd have no money and benefits. I also don't want to start a new job until my documents for work all show as male and therefore I can work as stealth (aside from whoever deals with the insurance papers). I do
NOT want to have to go through this bull->-bleeped-<- again at work. However, I won't be able to legally apply as male to workplaces until April. So, I have at least 4 more months in this Hell hole.
Working here has become very toxic and difficult for everyone, not even including my trans issues. In my state I can be fired for being trans and not be protected. However, I'm sure there are national laws that can help you if you're working in a hostile environment with harassment and dealing with insults and upper management does nothing about it.
I'm going to document this situation and any others that might happen. That way if they fire me over BS charges I can use these against them if I go to court. My questions are does anyone else have any recommendations? Especially if you've went through this before? Should I talk to any legal people or document other things? I'm so angry and disappointed right now. This place could burn down and I wouldn't care.
I'm so sick of this ->-bleeped-<-. Many times I feel like I have no future and things will never get better.

tl;dr If you think you can work at a place and be known as trans you will have a hard time. Go stealth.