I would try to be open with your feelings but start off slow. She has a lot of training and might think you need to go to the hospital and all you want to do is talk. each person is different and she might not see that. she is being protective because she cares about you. I noticed that with my girlfriend she has a degree in nueroscience and when I tell her things sometimes she tries to say the brain doesn't work that way or in her experience its different. You two have been together for a while I would try to open up slowly to her. Maybe then we will see if you really want to act on those thoughts or not. I have also noticed with the doctor I have now and the meds my thoughts of suicide or self harming have lessened.