Unless you can verify by independent means (not taking her word for it) that she has ended all contact with OM, then you should assume that the A is still going on.

If she refuses to leave the house then it's even more important to cut off all financial support for her A. The longer you tacitly approve the longer she's going to keep it up.

If you love somebody, set them free.
http://tinyurl.com/2empx2g