TBH he doesnt sound like a good match for you, if "I feel that i always have to watch my words with him in order not to set him off. This has curbed my spontaneity and i developed anxiety attaks. ". Also, you live hundreds of miles apart. Also, you want a baby and time is running out, and he doesnt seem ready to commit to that. I don't think any of these reasons are trivial when considering how well matched you really are.
This reminded me of a cousin-in-law who at 42 ended a decade old relationship with her younger(like in your situation) partner (because she wanted children and he didnt, amongst other issues), who then at 43 got pregnant by a new guy, and then married, and now she has a healthy son, step-son, a whole different life in these respects and seems very happy with it. She got lucky. I think you really need to sit with yourself and work out what your priorities&options are now, at 38.
As for being selfish, yes I agree with your b/f. Your timing was lousy. Don't beat yourself up about it, these things happen. It's not always apparent where someone else is at when dealing with such a huge loss, but the point is he doesnt want to have to deal with your 'stuff' at the moment (even your great need to explain yourself and convey how bad you felt), and nor should he, he is deep in his own stuff. You say (and sarsparilla felt) that it's not the first time that he responded like this.... then I would suggest perhaps it isn't the first time that he felt you were being self-centred. Anyway, to emphasize, this point in time is not about you, it's about him, and his loss -- that's if you have a functioning relationship? I guess he has concluded that it doesnt function like that, when he needs it to.
Losing a parent to cancer can be truly horrific, it is not just that you deal with the loss, (he is probably only even begining to get to that point), but the demise over that period and death that you see can themselves be extremely traumatic, horrific, and it has other more far reaching (deeper) effects in your grief process. So cut the guy some slack. And cut yourself some slack, because this is not an easy situation for you either. So just make a very simple&sincere apology (but not over-emotional or wanting anything back from him), maybe send him a nice card, and say you hope that you can at some point both get the relationship back on track (if you still want to Cpll72) or at least talk about it, and say you are there for him to talk to as much or as little as he needs to talk, about what he's going through. I'm not sure what else you can do at this point with regards that.