If your mother is competent, no, you have no standing to get involved in this.  In this situation, all you can do is suggest to your mother that she file for divorce, and help her find a lawyer if she's okay with that.

If your mother's not competent, you still have to overcome the law's presumption that her husband has the most interest in her well-being, and you'd have to have some proof that he wasn't acting appropriately for her protection.  You would certainly need to spend a fair amount of money on legal fees, because this kind of case is rarely either easy or quick.