I'm sorry you are going through this. It is very draining to be in a relationship with an addict. I also understand that you are embarrassed to tell your parents. That happened to me. I'm an alcoholic and my husband is an addict/alcoholic. Been through a lot of ups and downs over the years. When he is clean and sober it's good but if he relapses I have to start relying on my parents more and it is embarrassing. The questions about why I'm still in the relationship. Was all my support for nothing? Etc., etc. It might help just to lay it all out for your parents. It helped me to talk about things very matter of fact.
An addict or alcoholic does benefit from support as the earlier posters wrote. But support can take many forms. My husband didn't get sober until I forced him to move out of the house. For me I gave and gave but until I said "honey, I love you but I just can't give anymore" Did anything change. He had to want it for himself. We also have two young children and I have to look out myself so I can look out for them.
Have you looked at the SR forum for family and friends of substance abusers? I initially came on SR for support in dealing with my feelings bout my husband and the people on that thread are knowledgeable and very supportive.
Good luck.