well, have you tried telling her you have self harming behavior, and you can say you have injured yourself, but leave out suicidal for now, or you can tell them you've had suicidal thoughts in the past, that way they are into consideration, but you could avoid the hospitalization
although, if you are considering ending it and if you have a plan or if you do make an attempt, it might be best for you to go to the hospital and see if theres another way to get the help you need