Ok so it appears my problem was right in front of me:
Now I can't be 100% certain, I may have another problem and somehow this line ruptured because of that but I don't think thats likely.
Has anyone else seen this? I mean its ripped all the way through cleanly, I just don't see what could have caused this. Usually when I see radiator hoses fail they get like pinhole leaks, this almost looks like it was under a lot of pressure?