It is not WAS's job to protect you emotionally. NEITHER of you know how things will work out. Don't look for a guarantee from him now.
CHOOSE to accept the emotional risks for the possible gains. OWN THEM.
No matter what happens:
(1) H will be all over the place. H will backslide with OW multiple times.
(2) You will be all over the place.
(3) The ONLY way that things will work out well in the long run is if you BOTH know for DAMN sure that it was H's choice to dump OW and return to you. Everytime you pressure him and seek guarantees, you lessen the likelihood of that happening.
Give H space. Don't reinsert yourself into an R unless you are comfortable with the level of honesty and emotional risks involved.
Guarantees and reassurances now are meaningless. You wouldn't ask a first date for a promise ring before accepting the date. Stop trying to do the same thing to H.
