Emotionally disturbed ex-boyfriend?

[Poppyon]

When I was 16-18 I dated a guy who two years old for 2 1/2 years. He was controlling and emotionally abusive after a few months of dating. I ended up mustering up the courage to leave him. After I did so, he made it his mission to tarnish my reputation. Multiple guys stopped dating me knowing he was my ex. I was socially banished. After MANY years of unhappiness, I met a friend of my sister who is six years older. We've been together for a year. Long story short we went to a neighborhood bar for his friends birthday; we avoid these places. My ex-boyfriend was there. His friend made a comment that "Oh, looks like she is dating a Nazi now." My boyfriend was unaware my ex was in that crowd. Upon telling him, my boyfriend got was raging mad because he had heard them making derogatory sexual comments about me - and he didn't know it was about me.. I tried to play it off like I wasn't upset, but my boyfriend saw it hurt my feelings. Later on my ex-boyfriend was standing at my back commenting loudly, "Someone wants me really bad." because my boyfriend kept watching him.

He took to social networking immediately saying I wasn't over him and that we broke up four years ago and he has "that effect" on people. My boyfriend saw this and flipped out. My boyfriend jetted off, found him in the bathroom, and threw him against the wall in the bars bathroom in a choke hold. He threatened him and dragged him up to me telling him he better cut the drama and grow up. He told him he will hurt him he mentions my name ever again. He told my ex, "You better respect her and apologize." He was being entirely fake - stuttering and shaking as he came over and said "There are no problems." The next morning I see my ex had wrote "Nig** you don't have connections. Suck my fuc*ing d**k...oh wait like your girl used to." Ignoring, threatening, physical action - none of it works. I genuinely believe my ex-boyfriend is delusional or emotionally disturbed from his abusive home life.
My ex-boyfriend hates me because I "abandoned" him. Its the "If I can't have her, I am going to ruin her life" mentality. He wants me to be upset, or to cause a fight between my new boyfriend and I so I am single and unhappy like he is.

I genuinely believe something is wrong with him, but how do I not let this hurt my feelings?