Is this too petty??

So I'm on tinder and several times I matched and talked to someone just to find them actually in a relationship after further snooping.

Although I don't know them or know their partners personally I feel angry for their partners getting cheated on. I've been cheated on so I know how shit that feels like. Twice I matched with someone taken, and once I found out I told their girlfriends about it and send screenshots.

My best friend says I shouldn't be doing that since their relationship is not mine to worry about and just to mind my own business. She also says me telling them is "ruining their relationship" and isn't doing any good but just upset people. I just think that the fact that the guy cheated means he ruins it, not me.

If they decide to stay with their partner, then that's their choice. But I still tell people if I know they are being cheated on.

I personally if my partner cheated on me I would love it if a stranger told me about it. Do you think what I'm doing is unnecessary and petty?

What are your opinions ladies?