Found out he’s attached 😐. Should I tell the soon to be wife?

Long story short I have a fwb. We met off tinder back in 2018. I don’t want to date him or anything. This week I ended up finding out dude’s hid the hell out of his relationship. He did say he had a kid but he told me he was single. Looking back, there were weird signs but I never thought anything of it. I found out through social media. He’s an aspiring singer and she shoots every one of his music videos/photoshoots. That’s how I just so happened to search her name up on Facebook. Her name and IG handle were at the end of all his videos, etc so I was just curious about the company and voila. Should I tell her though? Honestly I’ve been in a similar situation before but I was dating that guy and I told the chick but she just yelled at me and didn’t believe it and he ganged up on me with her as to look innocent. The reason why I kinda want to tell her is because I just feel guilt knowing his secret and not saying anything. Like, I think I’d want to know if I were in her shoes...in love with him, raising his kids, and supporting him and his career. I didn’t sign up to fuck someone’s man for two years straight. He knows how I feel about people who cheat. Dude’s trash and according to her fb, they’ve broken up a lot of times but they’ve consistently dated for the past three years and he proposed this past winter.

should I do it anonymously on a fake page or something? I was thinking about screenshotting his Tinder and just sending it to her off of a fake page then leaving them alone. But at the same time, I don’t want to potentially break up a happy home, you know? It’s just really bugging me at this point. He even used to pick me up in what I’ve now found out through fb, is HER car. And the house he’d take me to sometimes is theirs. We’d always just go down to his man cave. He told me this was because his aunt and little cousin lived there also and he didn’t want to seem disrespectful to them if they were to come home. I could go on but good lord. last time we had sex was last week.

Should I say something or leave it be and just don’t talk to him anymore? I’m just conflicted. I feel like shaking up his home would be shitty but not saying anything is making me feel shitty too.