My boyfriend doesn’t want anything to do with my mom, struggling with boundaries

I (25F) have been with my boyfriend (24M) for four years. For background he comes from a very stable family his parents have been married more than 30 years and he’s very close with them. My family situation is the opposite.

My dad passed away seven years ago, and I mainly grew up with him. My mom has always been in and out of my life, struggling with drugs and being unreliable sometimes not talking to us for months. After my dad died we talked more and I wanted to build a relationship but the cycle of chaos never really stopped.

Recently she has made a big mistake and was arrested for an aggravated DUI and possession of a firearm. This has caused me a lot of stress because I am worrying about possible charges, legal costs, and just everything that comes with it.

My boyfriend already was not comfortable with my mom since we rarely see her and she hasn’t made much effort to build a relationship with him. In the past he has said he wouldn’t want our future kids around her, which I understand but it still hurts.

After this arrest, he’s been even more firm. He’s told me he doesn’t like seeing me stress over her, that she basically “doesn’t exist” to him, and that he doesn’t want any part of the chaos or care about her. He moved here on a student visa and is now working on OPT, and has said he didn’t come to this country to have problems and I can tell this situation scares him.

I feel torn. I don’t want to lose the only parent I have left, but she constantly brings instability into my life and now it’s affecting my relationship. My brother and best friend always say she is family so I should love her and be there for her.

I don’t know what healthy boundaries look like, or how to balance my feelings surrounding my mom with protecting my own sanity and my future.

Has anyone dealt with an unstable parent while in a serious relationship? How did you handle boundaries without feeling like you were abandoning?