Getting crazy

There are times that when I can't control my emotions anymore because of too much pain I feel inside, I reach my limit and started thinking about bad things like hurting someone which always end up hurting my own self thinking that it's my punishment. I felt like it's my way to be satisfied because I deserve being hurt. After that, I end up crying while laughing and calling myself worthless, not important, ugly and a freak. I don't know what to do because that's the only way I know. I always lose myself.