Mothers indiscretion

My mother (68) told me about an online affair which she ended. Im pretty sure the dude is a scammer with reverse image search of what she sent. She disclosed that her relationship with my stepdad has been unintimate for a long time. My stepdad is on the spectrum and does everything he can to support and has raised myself and his grandchildren who is now 25. A couple of things - I feel awkward with this information we don't have this kind of relationship. Frustration - mu husband and I bought the unit they rent together to give them both housing security. And What the heck am I supposed to do with this ??? Aita for wanting to give her the truth bomb and reality check that she needs about her current circumstance and behaviour