Intrusive thoughts that don’t serve me

I am trying to accept that a long-term relationship is over and move on. I get these intrusive thoughts that interfere with my progress and then I get stuck in this loop of “what ifs”. Our relationship was good, but he has so much guilt and fear about hurting his kids that he’s willing to sacrifice us to assuage his guilt. Whatever the reason, it’s over, and yet part of me holds out hope that we’ll reconnect down the road. My question is really about how to stop the obsessive thoughts about him. Telling me not to judge these thoughts, and just let them be, is not helpful because I’m in a neural rut that does not serve me. This has been going on for a very long time, so I need an objective perspective to help develop new thought patterns that move me towards feelings of empowerment. Maybe a suggestion of what to put in the THOUGHT line of the model? Thanks, Kate