Hi, I'm guessing you have already visited a doctor considering your medical history. I'm surprised that your doctor never suggested you to go for counseling before as it definitely has many benefits and higher possibility of helping you out. I'm sure you would've dated this girl for many years due to which you feel a strong attachment towards her; so your state of mind is quite understandable. Please visit a counselor asap because you are having suicidal ideations. Make sure you are not alone for a long time as your close ones can help you distract from negative thoughts. Stay away from any kind of substance use as it could very easily lead you to addiction.