I see no rabbit hole. It’s called personal responsibility. If you feel your needs aren’t being met you need to talk to your partner. Because it’s actually not their job to meet your needs. It’s your job to meet your needs.
It is never OK to break your vows and trust. Talk to your partner about your problems or leave them. It is never the third party’s fault the spouse chose to cheat. Ever. Because it’s a conscious choice. It’s much easier to blame them than accept your spouse is an asshole who has no respect for you. But they are.
The Other Woman has their own issues, but they’re not a home wrecker. 👍