Why does he badmouth me?

Hi, I have been in a relationship with this guy for an year. Everything was fine in the beginning when we were just fwbf. Later he forced me in to the relationship. I didn’t want to as I had a bad past with being in relationship. He is obsessed over my ex and he couldn’t stop bringing him in every discussion. I do have some stuff that belongs to my ex and I’m waiting for his parents to pick it up. He just never understands that it is not in my hands. He always brings up my ex no matter what and he drives me to edge every time with that. One day when he did the same, I was very hurt and I went silent telling him that I can’t talk rn, I need some space and I will talk later. He just can’t handle when I get silent and he gets psyched. He never gives my space when I’m hurt. Sometimes he yells quite loud in anger and I would get terrified as I had someone in the past abused me. When I’m terrified I am silent and I tell him that I am I’ll talk later. I need some space rn. He never listens and drives me to edge everytime. One day, he went to his mom and told her that I’m a narcissist who’s giving him a silent treatment. Why would he say that? He never told her why I’m silent even though I’ve explained him several times why I’m silent. He never told her how he drives me to edge in order for me to get hurt. He also provokes me quite lot. When he provokes, if I don’t say something, that’s a problem, if I say something, that’s a problem. If I say something, he calls his friends and badmouths me, instead of telling them how he provoked me or how it all started. Why does he do this?
Why does he badmouth me?
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