7.8 ovarian dermoid cyst nausea urination, bloating and constipation had MRI dr says surgery. Waiting on a call back. Spotting too. Possible rupture?

Doubt it. Your symptoms are unlikely related to the dermoid. These don't rupture but can twist the ovary and cause acute pain. Your symptoms don't sound like that though.
Dermoid cyst. A dermoid cyst of that size can cause the symptoms you state. Your doctor is correct to advise surgical removal. It is probably not ruptured or you would be quite uncomfortable and possibly very ill. These cysts can cause ovarian torsion which is very painful and serious. Sounds like your doctor is taking good care of you.