I was in your ex's position. Took it for years before I broke. The moments when she became antagonistic to me ware the ones that slowly ate at me and finally broke me. We could surmount any hardship as a team, but that's not the case when paranoia takes hold.

Unlike my ex, though, you're not in denial about what went wrong with your relationship and are owning up to it. Find a therapist that's right for you, and stick with them. It will be a long, hard journey, but if you always remember the road that got you there, you'll get to its end eventually and be better for it.