Need help with letter to estranged father

Back story: My parents used to live together in Yugoslavia. When the war broke out and my mom got pregnant with me, they fled to the Western European country my mom was born in. They broke up when I was very young. I vaguely remember some play dates with my dad when I was in kindergarten and elementary school. Back then my mom introduced him to me as uncle Mike though, not my father Mikhail (names changed, but you get the idea). I eventually pieced it together though (no relatives or family friends with that name, dad’s name on my birth certificate, family members slipping up, etc). Dad kept trying to stay in touch at least until I was about 13 but my mother didn’t want him to and eventually he seemed to give up.

As a kid I was obsessed with trying to find him. Now in my late twenties I still get moments every couple of months where I wonder what he’s up to and what it would be like to have him in my life again. At the same time I’m hesitant, because I had to cut off my mother’s side of the family for being incredibly abusive, so all I have left in terms of biological family is the idea of my father. And the idea of him possibly missing me feels better than the possible reality of him rejecting me.

…………………………..

Anyway, on new years eve I got a little tipsy and decided to finally do something. My government offers a service that let’s you find out any citizen’s address if you know their full name and date of birth. Turns out, my dad lives in the same city as me.

So I have his address and could send him a letter. I just don’t know the right thing to say. I don’t want to overwhelm him. I just kinda want to put the ball in his court. I’m Autistic so I’ve never been great with new social situations. I think a long emotional letter would be too much, so I’m thinking of something short and simple that boils down to something like “hey, this is your kid (added identifying information). I never really stopped thinking about you and I’d love to get in touch with you again. Here’s my number if you want to talk or go have a beer together. If not, I understand and won’t hold it against you, I just couldn’t live with myself if I didn’t at least try to reach out”.

Thoughts? Any recommendations for how to phrase this or for what to avoid?

PS: There’s also the added plot twist of me being a transgender man. My dad probably thinks he has an estranged daughter. I’m one of those rare cases that knew from a very early age and wasn’t exactly quiet about it. But I have to assume that due to the lack of information in the early 90s, he just saw it as me being a tomboy with an active imagination, like the rest of my family did. I transitioned years ago, so nowadays I look and sound like whole ass bearded teddy bear. There’s really no way for me to pass as female and ease him into that piece of information at this point. No idea how to bring this up. But I’d rather mention it right away than get a positive response to my letter only to be rejected when he finds out about me being trans.