I'm so sorry. I hope you're able to be safe going to and from session today and that it's somehow helpful or at least doesn't further hurt you.
So, in terms of leaving a 5-year relationship, I struggled with that with ex-MC. (That may have been more like 4 years? I don't know.) But still, until we had the major rupture near the end, I didn't see how I could leave. Like, I thought I wouldn't survive it. But then the major rupture happened, We kept trying for a few months after that.
But what it came down to is that I felt I couldn't trust him anymore. No matter what he said, I just couldn't. I also couldn't feel the caring when he looked at me, but I think the big thing was the trust.
With Dr. T, we've had lots of conflicts--more than with ex-MC, certainly. But for whatever reason, I continue feeling like I trust him (which is what made me go back the one time I actually left). And if something happened in my life, I felt he was the one I wanted to turn to with that.
Do you feel like you still trust L? I know trust can fade in a relationship and then return. So it's not a fatal blow. But it's something for you to think about. I do think a break could help you to see it all more clearly. Even just a couple weeks, ideally with no contact with her (maybe you could meet with T once or twice in the middle of that time).