TBH does she REALLY want it to work, was the affair a means to an end, an escape route from this relationship?
You mention she hasn't asked for you back, she's told you she would have left you for him, she cried for weeks cause he dumped her.
Be very careful that she isn't playing you. What would have happened if he didn't dumper her, where would you be now if she HAD left you?
From the little information we have been given, taking into fact you have previously had issues, she has children from another relationship that hasn't worked, she has told you she would have dropped you for this guy who was 'the one', it really is time to call it a day if it was me.
I could never forgive nor forget.