For me, personally, if I were that far removed from the drama, I could never go back for one more round.
There is no "What if's" or "what if I'm wrong", he won't change unless he's working a program and unless he's committed to you and not another woman.
Just imagine for a minute if you will, all the wonderful healing you've done. Where you've found peace. Then imagine taking him back and wondering "is he drinking again, is he seeing her" every time he leaves the house. All that mistrust and drama all over again.
This is not to say it's not possible that he's trying to heal, but 4 months into sobriety is way too soon. He needs years to heal.
Ask yourself, do you really want to give up your peace to do it all again?!