Questions about a situation with my MIL

I just need to rant, but I would love advice on what to do. So before my husband and I got married, his mother would always ask me for money or to watch her kids. The only time she would talk to me is when she needed/wanted something from me. Then I noticed she did the same thing to my husband, but she would guilt-trip him into helping and make him feel like shit by telling him, “I sacrificed a lot for you. I didn’t have to feed you or keep a roof over your head.” We were only teenagers at the time when she was doing this. ALSO, before we got married, my husband went to basic training, and his mother had access to his bank account. She took all of his money, then had the nerve to ask me for some. She asked me to watch her kids in exchange for a trip to see my husband when he graduated from training, so I watched her kids for a weekday and night. Like we agreed. However, when it came time to leave for the trip, she told me she wasn’t going but went anyways. Now my husband and I are married, have a son. And she only messages us when she wants something, usually money. She asked me if she could take her grandson shopping, she’s never been a big part of his life, and he cries whenever she’s around. I told her yes because I wasn’t bitter at this point, but I would have to be there since he’s bf, and I don’t trust her with my son alone. Then she and her daughter started sending their mail to my house, without asking. This messed up my son’s insurance because he’s on Medicaid. I told her she needed to change her address because they caused my son to lose him, and she just laughed. My husband deployed a few days ago, and she acted like he didn’t tell her anything about it when it was time to say goodbye. She doesn’t care about him, only about his money. She lives in a shelter with her two kids, and whenever I see them, they smell so bad and are starving, but she has new hair and nails. I brought it to my husband’s attention how many times she’s stood me up and how the kids were, and he said he’d talk to her about it, but I don’t want him to talk to her anymore. Which is selfish, but I can’t stand this woman because of how she acts and how she treats her kids.