The worst

I just got out of my first major relationship. We dated for about a year and a half and I was absolutely in love, or so I thought. Paul and I were constantly breaking up and getting back together, he was pretty mean to me, he would say hurtful things, and just basically didn't give a shit about me. I was naiive and would make excuses and convinced myself that it wasn't a big deal and I was at fault too. We finally ended it back in November for good. I found out he was seeing someone else right before Christmas and it literally made me sick I would cry myself to sleep at night and just dwell on the whole situation. The fact that he didn't want or need me made me want and try even harder. I would call and text him throughout the day with no reply. I went to his work a couple of times and begged basically. I never really realized how pathetic it was until right now. I went to his work today and got all cute and basically tried to make him remember why he loved me.
He point blank said "Erin, I dont wanna be with you, Im trying to tell you your a stalker and to go away." I was SO embarrassed I left crying and feeling the biggest psycho in the entire world. So basically what I wanna admit is I am having trouble moving on, Im not quite sure how and I dont know why even though this person is the biggest asshole on the planet and treated me cruelly why I would still want this person. I am insecure and am terrified that I will never be able to find someone again and that scares me. All I want is to find someone and be happy and if he is such a huge prick why has he already found that.