SSM: My boundary is that I will not live a celibate life. I am taking steps so that I can live my non-celibate life with integrity. I'd like you to be my partner in that, but if you choose not to be, I will accept that.
That's tough to do. And she might just decide that she'd rather just let that happen so she doesn't have to deal with her sexual abuse, or whatever it is.
And another thing that's tough for me is I truly hate the thought of her feeling forced to have sex with me just to save the marriage. And once I'd settled down, the sex drops off again. Which is exactly what happened to a close friend of mine. Had very much the same issues. Zero sex. Filed for divorce, moved out. Had a girlfriend. Ex-wife wanted him back. He went back, talked everything over. She had sex with him the first day back. Everything looked fine. He was sure it was a new era. A few months later, he told me she'd stopped having sex with him again.
Now, that's the only such divorce-threat experience I know of personally. Some of you on this forum seem to have had better luck, which gives me some hope.