Why, oh why?

So about a month ago, my ex and I aplit for good.  We had spent 6 months "broken up" but still saw each other on a more than regular basis.  Then after all of the terrible things he did to me, I decided I wasn't doing it anymore and I walked away.  And that's what he wanted, too.  Me out of his life.  Sounds like everyone got what they want, right?

Wrong.  I know I'm better off without someone lying to me and treating me bad, but I still love the asshole and I miss him.  I have stayed strong though.  No sense trying to be a part of someone's life when they don't want you in it.

Well the ex has contacted me twice within the last five days.  Once to just shoot the breeze and chat (which I called him out on) and once to apologize for all of the things that he did.  After the first time, I thought no big deal.  He's bored, looking for someone to talk to and curious if I'm moving on and doing ok without him.  After last night, I'm starting to think he really regrets a lot of things.

Romantic comedies make it look so easy to resolve all conflict and wrap up relationships in big pretty bows as the credits roll.  They don't tell you how long to wait and see if someone regrets hurting you, or when to cut your losses and walk away.  I know it would be almost impossible for me to ever trust him again, so that should tell me to walk away right?  But I KNOW that deep down I fell in love with him because he's a good guy.  And he has some growing up to do.  Do I let him grow up before ever giving him another chance?  Do I make another attempt?  Is there a relationship god with all the answers???