It sounds like you have lots of conflicting feelings. You want to be her friend but you want her to reach out to you first. You want to go to the baby shower but you are not sure how welcome you are since it is a surprise. You want to make up and let go of the problems from high school but you don't know how. Is any of this correct? Or I could be way off.

Perhaps you and she should go about getting to know each other as adults because you are not in high school anymore.

Meant to be helpful here but if it is not disregard.