My therapist is dating my ex

I just discovered that my therapist is dating one of my ex’s. I found out by accident through facebooks suggested friends. I saw a ladies profile pop up. Her profile picture was of her and my ex. I thought thats weird that fb would suggest I be friends with my ex’s new lady. It turns out it is probably because we have one mutual friend who is my next door neighbor. I noticed the first name was unique and the same as my therapist. But the last name was different. I clicked on the photos and realized it is indeed my therapist using a different last name on FB.

My question is now that I know this should I tell them? I would like to hear thoughts from other therapists.

For a little more context. This ex is a high school friend and we dated casually for a couple months. It ended mostly amicably with us going our separate ways. It doesn’t bother me that they are dating. In fact I really like her and she is a great therapist. I am worried that it may bother her and she’ll drop me as a client. Which I would understand.