If you were being cheated on, would you want to know?

This is a throwaway account for obvious reasons, and I am expecting a lot of backlash but willing to take it all as it is deserved.

I’ve been involved intimately with a guy in my hometown for the last 9 months, both emotionally and sexually. He’s in a committed relationship and his girlfriend is 7 months pregnant. I never meant for it to get this far, but it happened and I feel horrible. I tried ending it multiple times but he keeps sneaking back into my life seeking validation and comfort. I hate him for it and I hate me for it but I can’t seem to get rid of him.

My question is, as the significant other, would you want to know? I’ve debated just telling her knowing full well the extensive damage this will cause, but a part of me knows that I would want to know if I were her. I feel like if I told her it would be my way of ensuring he’d never come back into my life. Or do I take this secret to my grave in hopes of protecting this poor pregnant girl and her baby?

I’m really torn. I’m fully aware I’m the villain in this situation and I’m currently not talking to or seeing him.