Ladies any thoughts?❓

Lets start off like this..

You start dating a 24 year old man hes very sweet, charming, everything a woman could ask for. 1st month is perfect, 2nd month perfect as well (you know all his family and even his own child already), halfway to the 3rd month you get a message online. Another woman around 19/20 with 3 children stating that she is also dating your SO. Admitting that her children are from another mans and not your SOs'. She asks how long you have been with your SO you say "almost 3 months" and she lets you know shes turning 6months with him.. But had lost contact with him since he would ignore her. And that he had just messaged her a day ago cutting the relationship..(you ask her for proof, screenshots etc but says her phone does not screenshot..its 2016 by the way).. After work you confront your SO and he says nothing is true.. Since she had no proof at all you let it pass..maybe its jealousy from her is your thought...time passes and its 2 years almost 3.. Newly engaged and very bump into her and she finally is able to show proof..

*****WHAT DO YOU DO?*****