I can relate to this a lot. I have struggled with depression for well over a decade and am recently getting better without anti-depressants. I have struggled with negative thoughts and I find, activities provide some relief, but having meaningful relationships with trusted friends is vital, having people you can look in the eyes and express with honesty the negative feelings, the pain, and the hurt, and have them be present.
I know today I have a life worthwhile. I may never be complete in the physical manner, but I have a job I love, and people who love me. It would be the act of ultimate selfishness on my part to end things. I also believe I would be doomed to repeat this over and over until I live my life out fully to the best of my ability.