You're both in your 20's right? So really I'd say it's time to live your own lives. Parents always disagree with the decisions their kids make. If they are okay with her being bisexual, then I doubt that the announcement that you two are dating (which they probably already have inferred) is going to end their family. Even if it does, it's not your fault. You are allowed to feel how you feel. But ultimately it is your girlfriend's decision to tell her parents. Just support her either way. In the meantime just be mature, be responsible and rational, be an adult.
Prove to them and yourself more importantly that you are a good person and they've got no right to judge you.
Good luck!
Prove to them and yourself more importantly that you are a good person and they've got no right to judge you.
Good luck!