Harassment

My moms x bf is constantly bothering her because he wants to get back with her he showed up at my job , my two brothers and my mom job and is constantly banging on our door wanting to speak with her , then he calls my cellphone and leaves a message to speak to my mother so I text him this .. My mom is making me seem like the bad person because she said you don't bite the hand that feeds you ! Am I wrong ? 
​Ps he called me stupid and said I'm the reason he didn't marry my mom ( mind you they were in a relationship for 8 years so how am I to blame )