What do I do to stop letting this effect me? Am I over reacting? Need advice:(?

I am a girl with two brothers, one older and one younger. My brothers have always been pretty level headed and I was the "problem child" but I have thankfully managed to over come my poor decision making ways. My big brother jokes around about cutting (self harm) to me sometimes and it upsets me because I used to cut and he sees and knows it. I was not a 14 year old looking for attention or following a trend, I was a 19 year old overcoming drug addiction and though I haven't cut for a year now sometimes it still crosses my mind and I still bear the scars which I put oils on every day trying to get rid of. Every time he jokes around about it I feel undermined and I don't want to say anything because I know he is joking and I don't want to seem like a prude or overreact. ???