Pistol grip pump on my lap at all times

So I come out of my room the night before last, and "EM" (mom's soon-to-be ex-b-friend) follows me to the kitchen asking "what''s this?". I'm like "what's what?". He picks up the mail that I had brought in earlier and turns the pile over to the bottom where there was a square of butter stuck to the bottom letter (which, of course happened to be his). I told him I did not see the butter there, but of course he thinks I did it on purpose. THEN, he shows me this paper plate and asks me why I put it into the garbage disposal. I told him I did not do that, but he acted like he was convinced that I did. Then he started talking shit and told me not to "fuck" with him like 3 times, so I got really pissed. I told HIM "well, don't fuck with ME!". After going back and forth for a bit, he got all hot headed and I guess he was trying to scare me or something, so he took off his shirt acting like he was gonna fight me as I was hooking my dog up to take him for a walk. I told him to go ahead and make the first move, which he wouldn't. He kept talking shit and calling me all sorts of names. I told him again "I'm right here, pussy, do something then." Again, he would not. I said, "yea, 'cause you know your fuckin' ass is going to jail, bitch", then took my dog out (my dog by the way would not hurt a fly, so that was not a factor, lol). We ignored each other the rest of the day until my mom got home. That's when he started talking shit again ( I guess to impress her - what a fucking idiot!). Once again, I told him if he wanted a piece of me, I was right there. Then he did the dumbest thing he could have done. He threatened my life in front of my mom! I mean, what a fucking moron! Needless to say, my mom wants to kick him out, but he will not leave. She refuses to get the cops involved because she fears he will retaliate (which I agree with). This guy is a fucking psycho, and I DO believe that he will kill me if he gets a chance to do it, but his dumb ass already made the threats in front of a witness. So, here I am in the house just waiting to see what the fuck happens. My mom is convinced that he won't harm her, but I don't trust him worth shit. I've been carrying a piece on me ever since the threat. I'm a peaceful guy, but if he tries to harm me or anyone I love (including my dog), I WILL take his ass out. Also, I'm convinced that the whole paper plate thing was something HE did to try and frame me. Think about it logically. First off, there's no way that the paper plate could have just fallen into the small drain hole. SOMEONE had to crush it up and put it in there, so this was no accident. Second, if I wanted to "fuck" with him, why would I put something in my MOM'S garbage disposal? If I wanted to fuck with him, I could easily key his car or fuck up his flat-screen TV. There are plenty of other things I could do that would not affect my mom. His story doesn't even make sense! What a fucking asshole.