Doomed relationship

So I've just been hit with really big news and it's going to mean a lot of changes in my left starting in August. I wasn't expecting this at all and so it's a big shock. I'm supposed to be happy about it because this is my dream coming true but I'm just not. I'm emotional and upset because it means saying goodbye to a lot of people I really care about. One being my boyfriend. I moved a lot as a child and I can have a hard time adjusting to new situations and he knows this. He thinks it will be better for me to go unattached so that I'm more or less forced into adjusting and making friends. So basically I feel like my relationship is already over but I'm clinging to shreds of hope. I love him a lot and he's such an amazing guy. I just can't face ending it right now. 
Last night my boyfriend and I had sex and he couldn't get it in. I was too tight. I know that means I wasn't aroused enough and I guess I know why. But we switched positions and it was ok though I wasn't really in the mood. I faked it a bit for him because I did want to have sex but I also felt awful. And then I started crying in the middle of sex. I didn't tell him what I'm feeling because I'm scared we'll just end it right now and I can't face that. I just told him I'd tell him when Id processed what I was feeling. I just feel like every time something or someone good domes along its always at the wrong time and something always happens and I end up broken. 
I guess I just needed to get that out. But any advice or stories of getting through something like this would be really appreciated. 
Note: both my boyfriend and I are in our early 20s