It doesn't sound like repeating this cycle is helping any. Have you considered just stepping away from relationships altogether for a time while you seek out help/therapy/resources? I've been single for 5 or 6 years now and while maybe that's too long for most, it really helped put a lot of things (past mistakes and patterns) into perspective.

"Forever" and "never" thinking are some of the worst parts of depression. It's not too late to get some help and have a heart-to-heart with yourself about what you really want and need in life. Putting a wrench in the cycle and current situation doesn't equate to alone forever.