Co worker said I’m not a mom

I’m a step mom of almost 20 years to two beautiful grown women who I’ve helped my husband raise from the age of 10 and 12. Their mother was an abusive alcoholic who died when they were teenagers. I’ve put them through college helped with sex and dating driving, school, all the typical teenage stuff and basically have helped them deal with the abuse and death of their mother as well. Mother’s Day is Sunday and my coworker said to me I’m not really a mom because I didn’t give birth to the girls. Damn I almost lost my mind. I basically told her that I was more a mother to them than their birth mother ever was and here’s why. Just because I didn’t birth them doesn’t mean I’m not a mom. I’m so beyond hurt and pissed off right now. She’s on vacation for the next three weeks so I don’t have to see her for a while which is good but I’m still really shocked that she would say such a thing to me. She’s always been so sweet to me. How do I move forward from here?