Oh Crazy, it's not your fault whatever happens.
I can see that you have a deep seated belief that this is all on you :( I recognise it, which is why 
But I also know (now!) that it wasn't true for me, and it's not true for you either, however much it feels to be true.
When people said that to me, I found myself explaining how it's complicated, and I truly believed that Our Relationship was different, and that other people just Couldn't Understand.
I wouldn't have put it like that at the time, of course. But that's what was going on in my head, a genuine sense that it was all on me, and the critical choice was my fault alone. And if other people couldn't see it that way, it was just that they didn't really understand it, that our situation was so much more complicated and difficult and different.
And in many ways, that was true. But, not in the ways I was thinking. Definitely not.
Ringing any bells? It's ok whether yes or no btw :)
Anyway, if you can find any brain space free at this horrible time, please just start digging into this a bit more. I think it will help you.
There's a way of exploring stuff called 'laddering' which I think is useful at getting to the bottom of why we think the way we do. You question each 'rung' on the ladder, so you end up following back your belief to the root of it all. Also allows you to see why you feel the way you do and identify any steps in your thinking that are rather wobbly or you want to challenge...
So, start with 'if we split up, it's my fault', that's your first ring on the ladder. Next step up is 'because...', so you work out the end of this sentence 'if we split up it's my fault, because xxx' and then you step up another rung and answer the next 'because', and so on and on until you've got to the end of your 'ladder'.
It might give you some things to think about, maybe about these type of things:
- how much you take responsibility for things (more than you should, & more than you'd put on anyone else)
- how little you think your own self deserves
- how much of the fundamentals you can miss out on, and still expect yourself to live like that, and force yourself to 'be happy' without...
like love, respect, peace of mind, privacy etc
Anyway, sorry if that's not helpful, but hoping it is... 