There’s nothing wrong with being gay, I agree. But there is if you have already made the choice to get married and have a child because then the impact is much further reaching.
There is an impact, yes. And yes you chose to get married and you have a child.
Many people make that decision. Then they fall out of love. Then one person cheats. Then one person doesn't like married life. Then one person falls in love with someone else. Marriages break up daily and for a great many reasons. None of them are pain free and without consequences for the children. Most of them though are probably better off out of an unhappy marriage, than stuck in a dead one. And that goes for the children involved too.
I'm sorry your friend has distanced herself. There could be many reasons for that though - and yes, she may think you fancy her, in some juvenile way. She coukd also simply not know what to do to help you and be a bit overwhelmed with the information. Maybe she feels bad for your DH and doesn't want to be involved, even though she's your friend. There could be a host of different reasons.
But OP, you haven't made a mistake. You didn't know! You did what felt right at the time. Given how upset you are about this, it's fair to say that if you had known before, that you wouldn't have made the same choices. You've actually done nothing wrong here. Not yet, at least. Things happen in life that are outside our control and there's truly nothing we could have done to prevent them. How we respond to them, however, is in our control.
You can get divorced and spend some time making a stable, happy set up for your child. You don't need to be in any relationship. It truly can be ok. Some people will be supportive in a divorce and others utter dicks, but that's how people are.
You have done nothing wrong, OP, you're the same nice person you've always been.