Who the bloody hell said anything about being offended. It's just disgusting that's all but everyone's different.
I say fuck it and go for it. An orgasm is one of the best cures for monthly cramps and if you can get over it, (and if she can get over it, too) then there's a lot of pleasure in store. Just make sure to be prepared for the mess and avoid saying, "Ew!"
Just let her know YOU really want to, that way she's not all insecure and feeling like you're doing it because she expects you to. I wouldn't suggest oral sex, but when it comes to fingering, just lay a blanket down and go for it.
Ask her about it, lots of girls feel differently about having sex when their having their period. Personally, I don't mind at all.
Oh, sure, I've fucked and eaten bloody pussy. Didn't bother me at all. I am alive - and I am not afraid.
I would ask her, but most girls arn't comfortable with it. Just because it's messy, and sometimes (this is gross) smelly, and she might feel weird about it, and you might not enjoy it either. You should still ask her though, if your relationship is at a point where you can really talk about it (which, you should be, if your fingering her)