I know it may seem overwhelming to make yourself work out like you used to but it may help you... especially since you used to work out a lot and your body was used to it an now you've stopped. It might be a first step to getting back into things if you can make yourself do it.
A lot of guys don't want to commit... I bet this guy really did have strong feelings for you but got scared off from getting too close/serious. Just a guess. There are also the guys who are just a**holes who will say they are falling in love just to woo you or whatever, but you can probably judge which type of guy he was.
I'm sure it was crushing, but don't let it get you down too much... There are plenty of good guys out there and you will find one if you keep putting yourself out there.
I'm sorry things are not going well for you at the moment but they will improve. I've lost my lust for life too and am pretty tired of it - many people here can relate to that I promise you. I'm glad you found this forum, it's really great for venting and getting advice and I think you will find good support here
Monster bear hugs to you