Is it really possible that your feelings will change in 1 day?

Ive been for a year now with my boyfriend, the whole time we were been together he cheated 4 time, numerous lying, careless about me and really a jerk (of course we had a good times too). yesterday I found out that he lied to me again, and that he cheated to me again. I was soooooo devastated, crying the whole day, and at night we talked and I beg him not to leave me and he said yes he will stay, that he still loves me and he wanted to fix things (about him and us). he promised evrything again but I felt he will not... I was still crying the whole night.slept. and when I woke up..feels like im done of everything, I didn't cared at all. I ddnt called him. he went to my house and I really dont know what happened to me, I broke up with him.. and now Im not crying at all.. Is that possible? or am I just in denial and sooner I will blow up?...but thank God I feel like this now.