Hey Jacob! It sounds like you have got a lot going on I right now :\
Self harm can be quite addictive i know from personal experience! but you can get help! I know at this point you think you can't live without it but you can! You dont deserve this!
Have you tried talking to a conuseller? At this point I assume you are in school or college! Every single school has a conuseller and since you are 18 they don't have to tell your parents that way you can get the help you need and deserve without adding any more stress to them if that's the way you wanna go! But if there is any way you can tell them I really think you should! There your parents they love you and they will help you out!
In the meantime if you ever wanna talk
pm me! I'm sorry I can't be more help but just know your not alone <3