I’m so confused by the original post, I had to read it 5 times to work it all out. How can you be heterosexual if you got with a woman with woman’s bits? I got even more confused that you’d had children, I guess sperm donor ivf and you gave birth Much of the answers you seek are in the OP!
But, maybe I can help a little. I have a transman friend, known him for about 30 years. She was she, lesbian and vaguely unhappy at that point. Long term girlfriend was supportive but also a bit dismissive at times. First came the counselling, the mastectomy, the testosterone, more counselling, the legal documentation, the 'bottom surgery' etc. Somehwere in the middle there the lesbian girlfriend called time and left and there was a formal change of identity at work - one email form the boss "A is now B. We wish B well and expect that all staff will respect his choices. If there are any question please come to my office for a chat". There was hardly any kerfuffle, some people were surprised, others not so much. Life went on.
About a decade later he married my boss, a heterosexual woman with 2 kids. She knew him from a time just before his final surgery, so was aware of his/her status at that time. Neither of them see themselves as gay. He gets his sexual pleasure, as OP says her DH does, via a gender dysphoric kick!
It is ony odd when you look at it fro a disinterested perspective... it seems natural and right when you are personally involved.
Which is the very basis of the TRA agitation and the reason so many women don't see the GC perspective at all!