Expose his cheating ass or leave it alone. UPDATE

Okay so this Is kind of confusing but basically I have a cousin named John. He is married to his wife, Ashley. Ashley has a sister named Elizabeth and Elizabeth has a boyfriend named Blake. (All fake names except for his😬😉)

Anyway, recently I got a tinder and was scrolling through and I see Blake. I decided to like him to see if he would like me back and he did. (I wasnt 100% sure him and Elizabeth were still dating) I noticed his profile pics were him with Elizabeth cut out of them 👎. Anyway that night I'm scrolling through Instagram and I see Elizabeth's post because I follow her..its a picture of my cousin, his wife, Elizabeth, and blake. And I'm like REALLY. They were all on a trip together. So they just got back from their trip and Elizabeth goes back to college out of town and I got a message from Blake. I'm close to John and know Ashley well but I'm not close to elizabeth i just know her mutually. I Know her and Blake have been dating for years and I just thinkit's disgusting. Should I tell her or leave it alone since we aren't that close?

He hasn't said anything flirty yet because I haven't replied but his bio says that he is looking for someone. BITCH U HAVE SOMEONE.

UPDATE: so I took Brittany's advice and told my cousins wife. She said that she appreciated me telling her, hes done this before, and hes a POS. I guess she will tell her, I dont know, but if i hear anything else I'll make another update.

Another update: She talked to both of them and apparently it's a big "misunderstanding" and he is not cheating and never would and I'm just like 🤦‍♀️ so now elizabeth is gonna hate ME. lol