why am i missing him again?

i have been so much better the last few days,i think after stbx was absolutly vile to me on saturday i seemed to face up to the fact that i dont need him anymore.I dont need to be treated that way,i dont deserve the crap he throws my way all the time.we have had no contact since saturday and ive asked the kids not to mention him or OW to me.Ive started to look forward in my life again and he isnt a part of it.But the last hour or so ive been really down for some reason and i find myself mising him again.How on earth can i miss someone that repeatedly ripped my heart out and jumped up and down on it?I really cant wait for a day were hes not in my thoughts at all.