Everyone is telling me to let go...

I really wish it was that easy as the words imply. He hasn't really spoken to me properly since this all began in June/July. I have tried to make contact, but no matter what I try, I am getting seriously ignored. Now I am beginning to think that Americans are rude. Or maybe it is just some states.
I do not know if this is one of his anxiety attacks, or if his depression has hit a new high and he just don't think he deserves me. Or even think I don't deserve him! Whatever way and whatever his reason I wish he would just talk to me. He has basically cut me off out of his life.. deleted me from all his friends lists and now just acts like I don't exist.  He told a mutual friend that "it didn't work out". It takes two to make things work doesn't it? I was not aware that we had any issues that needed working out.
Part of me is screaming to let go.. the other part is hurt and confused. We had four years together, it is like he waited for the four year mark then decided that enough is enough.. He was supposed to come here.. was supposed to be in a proper relationship. The day before he left I was lying in his arms, he was making me promises and calming me down telling me it won't be long till hes back again. I want so badly to know what happened.
I got a big box today. It has the intention of packing away the numerous things that remind me of him. The thing is.. I can't do it. I picked up one of the many bears he has gotten me over time.. and just broke down as I remembered how and where we got that one from.
A friend suggested I ask him outright if he has any intention of getting back with me. I think I already know that answer as I remember him saying something along the lines of "it hurts me to know I wont be able to settle with the woman I love"..
How am I supposed to carry on? How am I supposed to let go when everywhere I go I see him? I walk past the local museum and I see him standing waving an England flag in front of one of the statues. I go to the park with the kids, he is messing about with them on a see saw.. its hard to explain to a child why you suddenly burst into tears.
The pain is very raw.. very very real and I am surprised that I am still functioning on any kind of level.
Do I not deserve my happy ever after? Doesn't seem like I do, I never seem to get my happy ending.
How can I let go? I love him and really found that out when he was last here.
I never have questioned if there is a God in heaven until now.. I always believed there was but now I am not so sure.