I've been through this not too long ago, and it took me close to 2 years to get over her, but yeah, it does happened from time to time after the initial few months, stuff will suddenly flood back and i will feel so lonely and extremely depressed. It's almost 2 years now and i barely think of her, but the harm she caused will take a lot longer to heal up. Still lonely though.

But for your case, i believe you ditch him for a good reason, i know it will hurt because it's comfortable to stay and hold on than to have no one by your side, but sometime it's best to let go than to hold on, because there's no telling whether he will change. It take time to heal, a lot of time, just be kind to yourself.