Do you think I need to tell the girl I'm dating she was overreacting
I'm not sure. Why do you think she was overreacting?
She called me weak
You should be honest when people are overreacting. You might offer to speak with them or get them professional help for dealing with stress.
You should always respect your lady without worrying about their emotions
You're right it is great to respect her, but that doesn't mean you can't worry about her ability to handle stress. It would be good for her to learn healthy ways for handling stress. She'll be healthier and happier.