Relationships are complicated. I guess, or better I am hoping that there are lots of things that you and your wife share and make you a happy couple, and that it is just this thing that doesn't work.
I can kind of relate. A lot of fights between me and my wife revolve around my music, more specifically: my desire to spend time alone to make music. My wife comes from a family and culture that is very social and where "alone time" is seen as somewhat odd. She wants to spend time with me. She thinks, when I am playing music alone in my room, that this is a decision against her, that I value my instruments more than her. She herself doesn't really have a hobby or anything she likes that requires solitude, so it is really hard for her to understand.
That said, although she isn't actively supportive of my hobby, she accepts it and tries to find a middle ground. She knows that I get cranky when I can't play, so she never really forbids me to make music, although I get the classic "you just do what you want, baby, that's totally fine" from time to time

She is okay with me spending money on it when she knows I'll be using the stuff, and I am not really spending big bucks that we would miss otherwise. A big plus is that she actually likes my songs (or does a good job pretending) so I play for her from time to time and, although she doesn't enjoy me spending time away from her, she enjoys the results, which kind of leads to the acceptance of the alone time. She encourages me to play little concerts on various occasions, but doesn't really understand that I need time alone beforehand to actually learn some songs.
Well, all that to say, I think you should consider two points: First, is it really about you playing the bass that she doesn't like, or may there be some deeper reason to it? And second, maybe there are ways to "sell" your bass playing to her, make her see the value of it?
And third, don't sell or give away your stuff. Especially if you actually are in an abusive relationship. If you are really unhappy about your situation and you can't talk about it with her (don't just tell yourself she won't listen, really try and speak to her!) you need to seek out professional help.