You should tell him, but for different reasons. Your reasoning seems more selfish, your motive to tell him should be that you want him to know, so he doesn’t go on being in a broken and unfaithful relationship. I think you should definitely tell him no matter what, but your reasoning is a little skewed, because telling him most likely won’t make you feel better.
Yeah tell him. That’s messed up. She had an affair and she knew both of you while having a baby with a partner she’s been with for years. This probably isn’t her first time having an affair with someone else. Just inform him because she’s probably putting his health at risk by sleeping around with other men. I would also get checked too. HIV is no joke especially if it goes untreated. If she breast fed and has it it could easily spread to her baby.
Yes, you should tell him, and you should dump your boyfriend. If you have any proof, send it to him, but it won’t make you feel better. Instead, do it because he deserves to know.
First, be aware: a LOT of people blame the messenger and not the person who cheated. So if you tell him, make sure to prepare for (in the worst case scenario) a shitty response.
That said, yes, you should tell him. He deserves to know that he’s been deceived.
Yes do it, if you were in the dad’s position would you like it? Being in the dark about everything?