Have you talked through your decision with your doctor? Does he know about your past addiction problem? There is also the possibility that Betaseron is causing some depression in you (which is treatable), and once you get through that, you'll be able to think through your decision more clearly. It's also possible that he'll talk with you about switching to Copaxone, for example, which has much fewer side effects than the Betaseron, and might be better for you.
The falling asleep all the time - are you attributing that to the Betaseron, or to one of the other medications you're on? MS-related fatigue will happen with or without medication, so if that is the cause, you'll not do much for it by stopping your other meds. You'll liklely still fall asleep -- and need to let your doctor know about this, so he can work with you on ways to treat that, or work around it.
You say you and your husband don't see much difference in your condition whether you take the medication or not. You do understand that the Betaseron (or the other disease-modifying drugs, Copaxone, Avonex, Rebif) won't "change your condition" at all..but may slow the progression of the disease? Multiple sclerorsis isn't like a disease where you can take medicine and feel better, see improvement -- it's medicine designed to slow the course of the disease so you don't worsen, not necessarily improve.
But yes, the decision does have to be yours, and your husband's, and your family. They're all stake-holders in this, not just you. If they all agree -- and you are sure you understand the possible consequences, then stopping the meds isn't life threatening (like it is with some other disorders). Just has the potential of life-changing.
...I am not a doctor, nor health professional, and don't pretend to be one, here.....