Natasha,

I know it's really hard to imagine at this point, but I firmly believe that people do come into & out of your life at certain times for a particular reason. You may not be aware of the reason right now, but in time it will become clear & as Spiritlite said, if you set him free & he comes back to you then he really was 'yours' & if not then he never was yours to keep.
I also take heart from the saying "what is meant for you cannot pass you by" the right one for all of us is out there somewhere, we just have to keep positive & carry on with our own journey until our paths cross.
Sounds easy when you write it down ..... if only !!!
Big hug & look after yourself
S
x