So yeah I was in a similar position as you and I went for it. I was with my fiance for 6 years and we ended up breaking up, but it could go either way.

I went for it because I just had to. Like, I knew I was trans, and I didn't really accept the possibility that I would live a lie for the rest of my life at that point. Once I knew, I didn't feel like I had much of a choice.

We broke up a year and a half ago. I will be honest, I am socially pretty outgoing and charismatic in some ways, and I have a ton of friends now (before transition I had like, a few but they were scattered across the country, none that I saw on any regular basis). Not sure how that would work for you, but I met a lot of them through support groups and dating apps. I now engage with art music in a way I never did before and I don't know if that would have happened also, but this is marginal and really doesn't have anything to do with being trans except that I don't hate myself lol and I met a lot of cool people through this process.

I do also have a girlfriend now, we are t4t and open, and we live together. So yeah, idk, it's different for everyone. I miss my ex fiance, I do feel like we could have made it work and I think she could have been happy with me. In some weird ways, less changed about me than I expected haha.

Oh and about telling her, well, I'm not sure which way you're going to go, but this person is really close to you. She's probably eventually going to find out. It could be an intense situation though, just be warned. But like, that might just be the situation you have to deal with :/

Before transition, my biggest fear was losing my wife. We had a conversation, and it didn't go well, and I went back into the closet for two years. It came up again when I couldn't stand it anymore. That time gave her the space to wrap her head around it, and when I came out again, she was more receptive. We're still together and very happy.

I've been with her for 15 years, so I know where you're coming from. If she weren't supportive, I probably wouldn't have transitioned because I can't imagine living without her.

I think you really need to have a talk with her. Maybe she's grown since you've last talked (like my wife did).

Just know that if you don't experiment and try with the gender stuff, these feelings are just going to keep eating at you for the rest of your life. You'll need to make peace with that.