Irritated.... Im not wrong!

So my son just turned 12 yesterday. My husband has raised him as his own since he was 1 year old. His sperm donor and i had a horrible relationship. I ended up leaving after enough was enough. I was 17 at the time. Still in school. Id come home and find a pissy/shitty baby that was not fed ect. While dude was sleeping all day. Well one day i came home when my son was about 5 months old. He had what appeared to be juice in his bottle. I flipped because he was ebf. I take the bottle and it stunk bad. There was about 6 oz in it. I asked what kind of juice when he begins to laugh saying it was wild irish rose (liquor) and that he gave it to him to help him teething. I had my mom watch my son from that point. One day when i went across the street to my moms he was giving my son a bath. Well i walked in and he began laughing. He was in the tub with him smoking marijuana and laughing because every time he blew in my sons face he coughed. I had enough and left dude. After that when my son was almost 2 he had made accusations that he was sexual touched by sperm donor. Got police involved and everything only for him to get away with it. He has not seen him since. Over 10 years. My son was hit by a car in a hit and run 2 years ago and sperm donor put on fb that he had to bury my son. Like wtf? He has not paid child support nor fought us on the name change of my son. My son knows my husband as his dad. He is wonderful to him. Always has been. Well today his sperm donor posts on fb a happy birthday post about my son... And somehow got a picture off my page (ive since deleted lots of people) and on his post he made it seem like he cares and it breaks his heart and that im the problem as to why he cant see him. Wtf? He messaged me last month asking how I was doing? Amd i asked why he was messaging me. He said he was making sure i was doing ok. Then proceeded to ask me if i would erase all arrearages he owes in child support ($40,000) and as i said no because whether my son is 18 or 30 he will have to pay him that money. That my husband and i pay for everything for him and his $0.43 he paid 4 years ago went towards a pack of gum. I dont know why he makes me out to be the bad person to everyone. Im more pissed he would steal my pictures of my son and post them. Because if it gets back to my son its going to crush him when he finds out his dad isnt his biological. Am i overreacting? Im stressed. We are 30 weeks pregnant and i dont need this.