<human>: Could you distill the essence of the text into 1-3 sentences?

I have been dating my girlfriend for 2 years now, we have had troubles like every relationship, but she has never really been open with me. This has put a huge strain on me as I feel like i'm opening my heart to her and she's still not letting me in, no matter how hard I try.

I've thought about ending the relationship before but always kept a positive output and it has worked out in the past. I've always known that my girlfriend has had problems with being away from family and stress from work but I never knew how bad it was until now. She has self harmed in the past but always told me it was over something minor and would get annoyed at me when I ask her to be open with me, as talking to others has helped me through dark times in the past I thought it would help, but it just pushed her further away. She came to me this week and told me she had gone to the doctors, she has been diagnosed with severe depression. 

I feel scared. I worry that any time i express a problem to her it will send her into a spiral of unhappiness. I feel trapped with my own emotions now because I don't want to upset her, I just want to make her happy. But now it is affecting my happiness.

I had been strongly considering ending the relationship because I'm not really happy, it just feels like the relationship is there, floating around without it being exciting or something to look forward to. But now she's been diagnosed with depression I feel scared to carry out what I feel best for me because I know how much it will affect her, she told me that I'm the only thing in her life that makes her happy. It will crush her if I leave her, but it's slowly crushing me if I stay. I don't know what to do.
<bot>: Girlfriend has been diagnosed with severe depression, feel locked into the relationship despite feeling like ending it is the best for me.