I could be way of base here but I find it a little cheekyfor a WAS to leave and then assume they can come back whenever/if ever they choose. Following that logic, I would tell him to let you know when he knows what he wants and at that time YOU will decide if that is what you want.
I am not saying to slam the door shut but to take ownership of the door. It is yours and you get to decide who can use it and when.
Until then try to refocus on you. Dwelling on this will nit help you. Plus it could take a long time.
Best wishes.
R 25 years M 14 years S11 & S13 Working on it alone since Oct 2014 M in trouble a lot earlier (~2 years) Feb 2016. 1st R chat in a yr. Next R chat Aug'17 Still together