My MIL thinks she tell us how to leave our lives and my useless partner thinks she can do anything.

I have a 2 months old baby and my MIL came to help us in the first days, at first it was supposed to be for 2 weeks but she ended up staying for over a month when I made myself clear that I did not want anyone staying longer because I need privacy to learn how to deal with my bob. A few weeks ago I found a that she wanted to leave with us for a while to “help” with the baby but I said no, because this is my first child and I’m want to do this on my way without someone else giving their opinion in the every single thing I do. She is extremely nosy. She got upset and started making this drama saying that she helped us, she spend all this money getting stuff for the baby and I was being ungrateful for not let her come back to leave with us for a while. All I said was: I’m not in a good head space; everything is new and I need to do this on my way. My partner bought her drama and gave me so much shit, saying that I was ungrateful, I don’t care about his family and his mother is just as important to our child as any of us. When he said that I lost my shit and told him that grandparents will never be parents and his mother needed to understand her place. I woke up a few days ago and I heard them making mean comments about me. I checked his phone to get a better understanding of the situation( I know this is wrong but it was strainger than me) and I found out messages of her saying horrible things about me. She said that I got pregnant on purpose and that I was taking advantage of my partners disability(he has autism) and I was not extremely manipulative and he should find a way to end this relationship as soon as possible so they could get a lawyer to take the custody of my son. And yes, the motherfucker of my husband agreed with everything she said. I feel devastated by everything I read, we had a massive argument and I said that this is wrong and she has no right over my son. I ended up calling her names and he spat at me , yes he spat at my face while I was holding my 2 month old son. And then I watched mash all my stuff, my family photos, the crystal angel my father gave me when I was 4, the rosary my grandmother gave me before she passed away everything that meant something to me, he said: you deserve it for not respecting my mother. My whole life I never thought I was going to live anything like this, I don’t know what to do. I have nowhere to go, no family here, no friends. have never felt worse. I’m now, living the worse days of my whole life. I don’t know what to do.