I believe you have gotten used to being abused. Its a horrible thing and you need to snap out of it. Being abused isnt the right thin, it will make you feel 'normal' again, but why would you go through all that pain.
Talk to someone about what your feeling. There are other things to keep you feeling alive other than abuse, abuse just isnt right for anything. I was abused, i was the same i felt it was normal as it happened over a long period of time, and i was only young i was 11 when it started. I told someone, they said it was wrong. It ended and it felt wrong, it was the way a grew up, and i was used to it. But i went to court and realised how messed up the whole thing was and how i was allowing it.
Its wrong to let anything like abuse affect you and make you feel its right, in now way is it right. Tell someone, take it to court, change your life while you can and get councilling or help orhterwise it will haunt you later. Its a difficult thing and i undertstand, it feels normal. But it isnt.