Angela,
The rational part of me is concerned for you, simply because it sounds like you might be stepping into a complicated, morally ambiguous situation. Back when I still thought I was merely attracted to trans women and not one myself, I repeatedly cheated on my wife. Worse than that, I often wasn't upfront with the trans women I was seeing about being married, or I fudged the status of my marriage, so I could convince them to get into a romantic/sexual relationship with me. I worry Mike might be doing this...
The emotional, visceral side of me is more like OMG! SQUEEE! I'm so happy for you! It sounds like you had a great time and he really likes you! I'm jealous!

You're a big girl.. but just tread lightly, sweetie.