Good morning ladies, i am in a pickle and just need advice at this point.

Backstory: my fiancé (J) and his ex (S) separated long before we started dating, around Mid-Late 2016, S started dating her now husband C end of Sept, beginning Oct 2016 and she had a child June 2017. They have not spoken since the separation, because they had a very toxic relationship.

So anyway, Last week, my fiancé best friend M, called him to tell him S is trying to find a way to get ahold of J, and he told M not to give S his phone #, just to ask what she wants and S told M that it was “a private family matter”. Now J ignored that because he honestly does not want to speak to S. Which brings us to yesterday.

J’s sister (K) messaged him screenshots of her convo with S which also showed a negative DNA test stating S husband is NOT the father of her oldest girl. So now we have to figure out what to do from here. Obviously, we plan on getting a DNA test to know for certain our next steps, but I’m wondering more if he will be liable for back child support for the last 7 1/2 years if the child is his? J is still not ready to speak to S because of the toxicity and trauma he endured during their relationship. I’m supportive of whatever he wants to do, if he is the father, I’m more than willing to stand by his side to face this situation head on and get through it together.