complicated (kind of trivial) situation, i need advice

Okay, heres a little background. I am 100% gay and legally able to consent. A female friend of mine is pregnant and the guy who she got pregnant with is bisexual and recently told her that he's attracted to me and wants to sleep with me. Their romantic relationship is complicated and I know she still has feelings for him. I honestly feel the same way about him and I'm tempted to actually go through with hooking up and my friend told me to do it "because why not" and doesn't seem to care whether I do or not, but I still feel like she'd be hurt if I slept with him. I know this is trivial but I'm really conflicted and I'd love some advice. Thanks in advance.