he dumped me:(

Chelsea
Today after 2 years together my fiancé decided to end things after a fight. He brought up the past and our past trust issues and said he can't do it anymore and we need to start fresh. He broke trust as well as I did in the beginning of our relationship...except he has a harder time letting go. We decided we loved each other enough to get past our issues together and grow and we HAVE. My daughter and I moved in with him, he proposed.. he is her whole WORLD and the bond they have is like nothing I could have imagined. And we just got back from a perfect weekend getaway trip. He gets insecure sometimes, he's tried to end it 2 times before and each time he changed his mind, but when he gets in his head like this he will say he's done and tell me to make moving arrangements and then come to his senses in 4 days or so...things have been SO perfect. As close to perfect as it gets. We have been more open and communicating more than ever. He told me to let my guard down that he was never going to try and end things again, that this was forever, and I DID. So much that we both decided to try to conceive. I let my guard down, I gave it my all, and this morning I got a faint positive. I didn't tell him yet because he told me to wait until it was a clear positive because of so many let downs before. 
Today, we got in a small argument based on his insecurities. And he decided he's done. Nothing will change his mind. I told him there's a high possibility I'm pregnant...he didn't believe me and said I say that every month. But he said if I am we will cross that bridge and figure it out then.
How can my kind, selfless, loving, giving man who buys me flowers, leaves me sweet notes, loves and spoils my girl like she's his own, throw it away just like that over insecurities from 2 years ago? Just this morning he told me to invite our parents over for dinner...now he's telling me to make plans to find a place of my own. This is the 3rd time this has happened. And every time he has come to his senses and realized he doesn't want to lose me after awhile. And every time it comes out of nowhere. And if I am pregnant, am I about to be a single mother of 2?!
I'm so heartbroken...