I am torn between just cutting it off and being alone for longer for the sake of being alone and processing the M ending
Steve, I think the reason the vets are not resonating with you is because they are overlooking the important fact that a lot of their advice is probably more applicable before you entered the new relationship. Now that you are already in the relationship and have already introduced your GF to your kids, it is a different scenario since you don't have a time machine to go redo things.
There are examples of people leaving relationships and getting into another one quickly and somehow making it work, which should give you some sense of optimism. However, in my opinion you need to do the work to properly balance the needs of your new relationship with those of your kids. You will need to enforce boundaries, not mislead your GF and continue to be a rock for your kids. Not easy to do, but other people have done it and perhaps you can too. Good luck!
