MIL wants to move in to get out of toxic relationship

My husband and his mom don't talk a lot. I don't want to go into his business but he just didn't have the best childhood. When she calls he looks at it, makes a face, and let's it ring. My MIL called me from a different number saying she needs my help "woman to woman." She's trying to leave her man who is financially and emotionally abusive towards her but she has nowhere to go and she's calling me because she knows her son won't talk to her but as a woman she knows I understand and is asking to move in with us. If I just move her in than that's the end of our marriage. She's just really making me feel guilty. I did mention to my husband that she called and told him what was said and he rolled his eyes and said nothing.