extremely quick to move on!

Ive posted before about my situation, the guy I have been involved with I have given numerous chances to and over the past 6 months I have helped him a lot with some severe problems he has faced.

a week and a half ago I told him I didnt agree with some of the posts he was writing on social networking sites, his repsonse was to end our relationship via text....these posts were mainly things about how great he is and on one occasion over 30 women 'liked' and remarked how they would love to find a man just like him. (Im sat thinking to myself yeah, if you can handle him sleeping with a colleagues wife, lying to you and being ungrateful of your help and support)...

we havent spoken since then and I took the bold step of changing my number.I sat thinking to myself perhaps ive been harsh and wanted to cry inside when I thought of how its gone.So last might i contacted him......
He acted as though he didnt even know id changed my number. Worse is, that it turns out today (less then 2 weeks) he is moving into a house with another woman. This woman he says is a "friend" and he dosent think of her as anything else. But nonetheless!!! When we were together he promised me the world, kids, a house etc. Yet couldnt actually move in with me?!! Im still in shock that in such a short space of time, someone can just line up others!

I know I have to move on with my life but im shocked!