I know you want to follow what the church says, but I hope your decisions are not hinged upon whether the M is valid or not. I would give it some consideration, but not live my life for any other reason than your W is out, unfaithful, and living her life.
You are doing great.
Me: 46 FWS: 36 Married and Divorced 4/07, Pregnant 7/07,False R 7/07 Baby Girl born 3/08 Kicked him out because OW: 7/08 5/10 He realized what he had and lost. Moved home! REMARRIED 3/14/11!!