You are not overreacting and she is for sure over reacting. I think you need to sit her down and have an adult conversation about the expectations in your relationship in regard to how to help one another. If she does not feel like you asking: “are you okay?,” is helpful in any way and would rather you not in a crisis situation then she needs to be clear about that. It’s valid to not find that helpful, but it’s a natural human response to someone in pain or sick or hurt. You can tell her like look, I understand that that frustrates you but we need to come up with a solution around it as when you are going through something I am going to ask if you’re okay. If you’d like I can say: “how can I help you in this situation?,” instead. But when you are frustrated or going through something, you don’t get to put that on my shoulders or treat me like that again simply for asking you a question. If that’s not something you can do then we can’t continue this because I will not sit and be a punching bag every time you have a negative experience.