Normal? Unfortunately it’s too common.

Okay? Absolutely not. Even if it breaks your heart, if you truly care about the person that rejected you, you would want them to be happy either way. It’s certainly not okay when there was no guarantee of the outcome, and not okay to be hurt by someone else’s decision.

The former best friend is either trying to change the girlfriends mind through abuse, or lashing out like a toddler refused a new toy. As you said, she’s immature, and showing it very well.

Some people say this girl is mean, crazy even

Very true, sounds like someone needs counseling.

others say she had the right to say that because she was hurt and my girlfriend should have said yes

Those people are very, very rude at best, and in my opinion, worth cutting ties with. Nobody should ever be made to give any answer or if guilt. If the girlfriend had said yes out of guilt, she’d be depressed and regretful for it every day. Anyone that shames a person for their own decision doesn’t have that persons best interest at heart.

I’m sorry this is happening to you, but you/girlfriends best thing to do is to ignore everyone that speaks ill of her choice. No friend would disrespect another friend’s choice (unless that choice is dangerous for the person that made it), and actively attacking them over such a choice, as I said, it’s only abuse.