Do not do this. Dont mention the wife being abusive AT ALL.
Dont mention him being abused, dont mention her being the abuser.
Tell him you want to be in his life... if that’s ok with him. ....tell him you’re always there for him. Do this
and the reason you don’t like his wife is because you see her as an abusive woman who treats him badly Dont do this
by telling him you see him as a victim you'll immediately put him on the defensive of his relationship, and of himself and of his choices and of his life.
Unfortunately some people can’t see that they are being abused or they love that person so much they don’t care. Exactly, they are trauma bonded.
Dont give him a reason to cut you off. Give him a safe space to exist in. Dont judge him or his choices; just be a safe, non judgemental person who is there to support him. Dont ask about her, dont ask about his relationship, don't question why he stays, don't say shes abusive or that shes toxic or whatever else you think about her.
By passing judgement on her; thats not a safe space for him to be in when hes in a trauma bond.