Hi Caitsith, welcome to SR!
I'm sorry for the reasons you find yourself here, but I can assure you that you are normal to feel the things you do at this point, given your circumstances. Addicts do basically abandon real life in preference to using, leaving loved ones hurting and alone. And it is a reality of addiction that it can result in death. So you are not crazy to have the fears you have, or feel the way you do.
Do you have any real life face to face support people? There are free support groups in
Nar-Anon (a support/recovery group for friends and family of drug users) and
Al-Anon (same for friends and family of alcoholics - since there are many more of these meetings in most communities there are often friends and family of drug users in them).
Please take some time and read the "sticky" posts at the top of the topics page for great information, and please feel free to come back anytime and post away to ask questions, vent, cry, feel your rage or fears, or report on how things are going. Members here will chime in with their "experience, strength, and hope" of what they've learned in similar circumstances.
Hugs to you! More folks will be along to welcome you shortly!
CLMI
P.S. - You are definitely in the right place, and welcome here!