The thing is you see your parents interact more than any other couple until you're with someone yourself for a while. It's going to be your model for relationships. It doesn't make him right, but it's understandable. That's why it's important to be careful who you choose to have kids with. The way you get along with this person will influence your kids for the rest of their lives. No offense intended toward
Mr Snek, nobody asks to be born, but if his mom was his father's only option, his father probably shouldn't have had kids. You brought your kids into existence, you owe them happiness and stability until they grow into fully functional adults. His parents didn't give him that and now he's all fucked up because of it.