How do I deal with my MIL?

So me and my S/O have been together 4 years. In the beginning of our relationship, I was in a great position.. good paying job, a nice car.. etc. My SO also had a great job, but was living with his mom at the time because he was a co signer on her lease & he helped her pay rent every month. In the beginning, I noticed things were off about her. She didn’t really like the thought of him being “spoiled” by me in her words. Sometimes I would come by and drop him off some food after he worked a 16 hour shift. I would get him small things like body wash, lotion, cologne. Even boxers and socks sometimes. Just because I wanted to show my appreciation towards him, he needed the items and because he works long shifts he never really had time. My SO comes from really bad poverty, with a toxic background and history with his mother. Who would choose men before her kids, let these random men abuse him physically, she got married to the man who molested, raped and inpregnanted her first daughter & they grew up not having a relationship with their biological father (who passed away last year) because she made it that way. My husband was always the punching bag of the family. Everyone always took it out on him, drained him of everything until there was nothing left and that was the type of environment he was in. He was starved and abused as a child, his mom would leave him at the ages of 6 for weeks alone with his 2 older sisters who were only 11 & 9 to figure it out on their owns while she got high and had sex with different men. When I came into his life, I gave him the love attention compassion and everything he never had as a child growing up. My husband was never a man to show his emotions, ever. he grew up on the mentality that men don’t cry. once he opened up to me let himself be vulnerable his life changed positively. His mom didn’t like the fact he had me around, because she noticed him start to sprout his wings. When their lease was over, he left. He was staying at hotels for a few weeks and we eventually got our own apartment together. That lasted for about 2 years. Everything was great.. RELATIONSHIP WISE..we got engaged & married. Our marriage was a court wedding we did alone, we wanted to be personal and after all it was a court wedding. The ceremony is only 5 minuets why make a big deal with other people?. Through the years we cut ties with his mother because she was beyond toxic, she would show up to my husbands job demanding money because she was his mother and if she needed something he was required to give it to her. She would come to our leasing office trying to get us kicked out, because it wasn’t fair to her that he was living with me and not providing for her. She would lie about being sick, just to get him to come visit her so she could ask for money.. she broke into my husbands car twice in an attempt to get money because she has a bad weed habit she can’t maintain with her disability checks. My husband and I welcomed our son a month ago and 2 months ago moved into a private complex that requires people to buzz you in to even get inside the apartment building. Guess who randomly showed up at the front of our building banging on the front door of the complex? My MIL. She’s demanding meeting my son, even though she knew I was pregnant, never attempted at any point in time to ask about how I was doing. She even bad mouthed me saying the baby probably wasn’t even my husbands child, and that if it was I need to leave my husband so he can’t be a father because he doesn’t know what being a father is like. We’ve attempted to talk to her and tell her in a nice way to leave us alone, but nothing works. What can I do about her? Me and my husband don’t want her anywhere near our son.