Just need a little uplifting or advice.

My husband and I have been together for 6yrs and married for 2. I know he struggles with mental health and he has a past of trouble with coping with it by "using". There has been times where he would get better and then he has not so good days. I have been by his said these last 6yrs by trying to be his support because truth be told, Im all he has that wants to believe in him. These last couple of months though have been hard. He is in a bad head space again and I caught him using again, and at this point, I just want to give up and let him go, I was recently diagnosed with Lupus and just that alone is hard and affecting my mental health. Has anyone been in my shoes? What should I do? I dont want to give up and I want to keep trying to have faith but at the sametime, I'm tired because not only with the Lupus, I still work a full-time job, make sure all the bills are paid up, and care of the household. Any advice for me?