Well you mentioned that OW was a big part of the issues over the past 2 years...not really...it was H's behavior and she just happened to be part of it.. Next...I would say that as long as he reacts to OW actions (i.e. breaking up with him, dating other men, becoming engaged, being jealous of you) then it would be too soon for him to come home...and be in a good position to stay...
I know my H came home too soon because his thinking was still in "crisis mode"...he didn't think and reason like the "normal" H I remembered...this made it difficult for me to deal with, to keep my mouth shut, and to be sure that he wasn't going to leave us again...it was not a good time for me or the kids...
If I had it to do over again...I would have still been there when he hit bottom but I would not have brought him home...I would have waited until he got the help he needed and it was working...
It was very very risky what I did...but then you know that because your H has come home, only to leave again...so you know what his actions are like...just because he feels bad...is sorry...is "over OW"...you know that is not what will keep him home IF he returns again...
NOW...my H reason's things in a rational way...a way that makes sense to all of us...I can talk to him, confide in him, and not fear that what I say will make him run for the door...and really that was at least a year after he came home...he should have been on his own...maybe he would have cleared up faster...maybe longer...but it would have saved me and the kids a lot of anxiety that we didn't need...
You know your H, Kissak...you know what YOU deserve...don't settle for anything less and you should be okay!