My ex mother in-law is crazy

My son went and stayed with his grandma a couple days because she keep complaining we never let her see him. Me and my ex set down with her and explain she has to watch what she say (she has no filter) and a set of other rules if she wants to spend more time with him. She seem to have got it so when she went back home we said he can go stay. That was a huge mistake. My son comes home crying telling me he sorry he messed up my life. When I ask him what is he talking about he tells me grandma said you and dad was doing fine and happy in love until you had me and that you never wanted kids you got pregnant and dad begged you to keep me but you really didn't want to. He then say grandma said you didn't have the patients for kids and you got frustrated easy which started you and dad to arguing all the time and breaking up and she told him because of him me and his did never had time for each other. She told my son that I was mad I couldn't get up and go like I use to and felt like I could no longer enjoy life and resented his dad for that and us not being together all came from having him. Needless to say I'm furious I called my son father immediately, when we confront her she have the nerve to say he deserve to know the truth. I wanted to slap that bitch. When ask why was it even brought up she said he was looking at pictures of y'all and wondered what happen. I almost jumped on her. I told her she will never see my son again or speak to him. She was a big factor in our break up honestly. My ex a mama's boy and he never stood up to her even when she was clearly wrong and she was always in our business I told her so right then, you want to tell someone it's their fault it's yours. I was surprised when my ex stood up to her with me. She is such a monster. I looked my son in his face and let him know I regret a lot of things but having him isn't one of them and I love his dad for helping me bring such a beautiful being into the world, he did not mess up my life but enhanced it and became my best achievement. The pain in my son face that his own grandma caused I will never forget. Her one and only grandchild, now she might as well not have a grandchild because she will never see or hear from him again. I will never forgive her. She keep saying she always told my ex the truth but she never paid attention to the stuff she say about my ex dad hurts him. She won't do that to my child.