Not because I necessarily disagree with the above two, but my thoughts are...

Do nothing with the information...

Here's the thing... the info speaks for itself. She is having at least an EA...

Confronting either your W or your cousin will result in some variation of the following:

+ it will be denied

+ it will be confirmed

What is very likely is, this behaviour will not end, but will go deeper under ground...

While you may feel good confronting one or both... it will be temporary...

So... the question is:

Does this information affect your stand and your DBing?

It is painful, yes. Some realize they can, eventually, forgive an A. Others... no...

The choice is yours... and whatever your choice... right now... it may change... over and over... during the next while...