My son keeps going back to his dumb fucking wife and at this point and at this point I don't wanna hear about it anymore

My son's wife got him addicted to drugs. It's the truth. Before people "Oh blame the women for everything". He was 18, freshly out of high school, she was 26. She convinced him to try drugs. She got him addicted which is why I don't like her. Now he's 24 now and has made the decision to continue being hooked on drugs so at this point I'm just disappointed in him. My son and his wife have split up several. He didn't even want to marry her. At there wedding I asked did he want to do this and he said no. There wasn't even a proposal, she just said they needed to be married. Whenever they split up he is able to manage to get sober but they he's an idiot and goes back to her. She has never been sober. Every time he goes back, he goes back to drugs. One thing I don't understand is why they stay married because they do not like each other. On Christmas they came over and his wife walked out because she doesn't like my step daughter because my step daughter isn't blood and doesn't want my son around women who aren't blood and he said "That stupid fucking bitch I hate her!" They fight so much. She's told him she hated him and wouldn't come to his funeral if he died. He says he hates her. She called him a piece of shit. A bitch boy. He calls her a bitch. They say they hate each other every other day. Why stay together? You don't like each other. He left her 2 months ago and said he was officially done and was gonna get sober for good. But he's back with her now. At this point I want to tell him to stop complaining to me about her. You choose to keep going back knowing you guys have this toxic abuse relationship. You know you can't stay sober when you're with her. But you continue to go back. I just don't want to hear about it anymore. He continues to go back so what can I do with him bitching about her