Controlling your feelings around someone you once loved is never going to be an easy thing to do, let alone if you have to interact with this person on a daily basis. People are quite prone to getting attached, and when its all said and done it's sometimes hard to just flip the switch. Seeing as though you can't completely avoid seeing this person more then you'd like to, I'd suggest slowing down the actual amount of contact you guys have. It may seem cold, or anti social but like any other hurt muscle, the heart needs to repair too. Constantly interacting with this person, trying to turn it from a heated relationship into a friendship too quickly may ensure a slow recovery. If you find yourself unable to talk to this person without reading more into his kindness then he actually means my best advice would be to seriously lower your contact with him until you feel stronger. He may get insulted, sassy or otherwise annoyed but he has to realize that what you guys have been through is obviously bothering you and he can't casually think its all going to be ok.

In closing, know that heartbreak is always going to be a hard thing to deal with. Whether you live with the person or not, recovery just doesn't happen over night. Read, write and mediate, look fondly on the times you two had together when they were good and discard the rest. Never blame yourself, blame the circumstances and breath. It will be ok...

-Nate Lovestruck