How long has this been going on, how old are you, to what extent does this occur..

Im 26 and this is new.
I recently started to talk about the way i feel when i cut myself (i cut since i was 19). I noticed that often when i self harm i get aroused.
I was abused as a child (dunno know how old I was, under 6 for sure) but there was no pain involved cuz i was only touched and the guy was "nice" to me.
So i dont think theres a connection.

I know its masochism, i just want to know WHY. Why i need this? Why i want it so bad.