There are plenty of scorned women in the world who, not having got the man to leave the life, have conjoured up all kinds of lies to try and get the wife to leave him.
I am not saying this is the case here. I am saying it is a possibility.
It is something for the OP to consider and to get to the bottom of. The OP might forgive one affair but, quite rightly, not numerous affairs.
Wouldn't it be awful if all the other affairs turned out to be lies made up by a Mistress scorned who didn't get the man? If the OW has lied about all the other affairs and the OP does leave her husband then the OW wins doesn't she - she gets what she wanted all along.
Bottom line, the OP should not be believing a single word the OW says - listen, take it in but think long and hard about what the agenda of the OW is in saying these things.
After all, the OW DOES NOT have the best interests of the OP at heart does she. When the OW was sleeping with the OP's husband - sorry OP - the OW did not care about the OP or the OP's DC. But now that the OP's husband the OW have split up along comes the OW wanting to warn the OP about all these alleged affairs? Isn't that suspicious?
Hang on, why wasn't the OW peeved off with the husband when she was sleeping with him - wasn't he supposed to be having other affairs at the same time also.
Doesn't sound right OP. Sorry. Be very careful what this OW and her friend tell you.
Best of luck OP. I hope you get through this and go on to have a happy life.