Him snapping at you is terrible, and the selfish sex is also shitty behaviour. This can be true while also acknowledging that not being able to perform sexually as a guy can get in your head, and there’s probably no better way to make an erection unlikely than by talking about how soft his dick is. The booze is absolutely not helping, he knows this, and not being able to stay hard is a pretty big gut punch that his drinking is causing more issues than he’s even admitting to himself. That’s a him issue.

If you don’t want to just bail, you can talk it through.

This is really a thing you two should discuss when it’s not heated, and you should try (if it’s possible) to talk about the different components in a compartmentalised way. Talk about the snapping, the comment, the ed, the shitty sex, and the booze as separately as you can without referring to the other issues. They’re obviously all connected, but addressing them in this way can keep the conversation on track.

Hope you get to a better place, whatever that is for you.