first of all you said that none of your family know what your going through and sadly that is almost alwasy the case. the feeling of being a si victim is one of lonliness and shame, i totally know what your feeling.
however your family might surprise you, try talking to them and explaining how you feel when you get the urge to si. its hard for them to cope with so you have to realise they may not handle it well and a lot of people try to "guilt" you out of it (ie think of what your doing to your family). this is understandable but totally wrong... explain to them that your already ashamed of what you do and that you dont need their feeling heaped on top of your own. explain you need support, not guilt because that will likely make you do it more.
as for other ways of dealing with these feelings try crushing ice cubes in your hand or punching a pillow, anything that can give you relief without injury.
meds also can be helpful but are not alwasy the answer, all they do is numb or mask the feeling, they dont make the problem go away... that is only something you can accomplish with determination, support and time.
finally as for the scars, i had my scars covered with a lovely tattoo that now symbolises to me the fact that i have come through it. aonly recently got it and this summer i have been able to wear short sleeve in the sun and get a tan
would this be something you can do? if not try bio oil or something similar