Talking to mom about my choice in joining the army?

I have talked to my mother and told her I plan to join the army and go in for 68w(Healthcare specialist), After that she bombarded me with questions and information about this job. she is freaking out that I want to be combat medic, and now i can't even have a conversation with her with-out this being some kind of way for me to hurt her. I told that this is what I want to do, and I'm going to do it with-out or with her support (hopefully the latter). I'm just wondering if there is anything I can say anything to help her understand this or if i just have to let time p. let me say again I try to talk to her about it but she won't have it