OMG why do my emotions go back and forth?

My boyfriend of 5 years (and 2 kids, 4yo & 7.5months) seperated 1week & a half ago. The first week, he came over everyday to see me & the kids, and we talked about working things out and were doing really well. Then on Thursday he started yelling & cursing at me anytime I tried to talk to him, and then Friday he came picked up his clothes & checked his bank account & left. Leaving our 4yo asking "Mommy, why did Daddy leave again! He didn't spend time with me" Of course, he started the fighting on Thursday cause the weekend was coming up and that was why he continued it into Friday so that he had an excuse to get clothes to go out. Well, Saturday we didn't hear from him all day, and then Sunday he came late in the afternoon and showed up with hickies all over his neck! I finally snapped. And kicked him out completely, told him he is not welcome back to the house. I also took my car back (that he had been using to get to and from work). I had to jump in the car as he was taking off and snatch he keys out of the ignition because he was going to take it ANYWAY. I also, out of anger, threw a hotdog at his face. lol. I know, it was either the hotdog, or my fist. And he started screaming he was going to call the cops on me for domestic violence because I left him a bruise on his neck. My repy was #1, he no longer lives here, so it's not a domestic violence situation. #2, he tried to take MY car after I TOLD him not to. #3, the bruise on his neck was from the girl who was making out with it the night before! He also told me the girl rubbed all over his "junk". Then he had the nerve to tell ME to "grow up!" my reply "grow up!? i'm home with the kids watching lady & the tramp, reading them a story every night, & tucking them into bed, while YOU are out gettin ur **** sucked by the first girl that comes around! who REALLY needs to do the growing up!" Anyway, I was completely hurt & hearbroken, but after saying the things I had to say, I felt absolutely great. And then felt even better the next day. But then today, I woke up starting back into my depression again. In 1 week I lost 14lbs, i couldn't eat, sleep, stop the crying...and today it's all starting up again, and I actually MISS him! WHY DO I FEEL THIS WAY? I WANT THESE FEELINGS TO JUST STOP! I WANT HIM GONE & to have NO feelings about him at all! How long will this go on before i feel better????