What should I do as I just don't know?

me and my family (my spouse and 2 kids) have lived in an apartment for 9 1/2 years. i've been afraid to move to a house with him as he has a drug habit (smokes marijuana) and he drinks occasionally. He has always paid all of the bills on time. He is a great dad. He is not so good to me. He has spent lots of time away from home. He says with family. He left me for 2 months last summer. He goes to bars occasionally. I don't as I don't drink or smoke. I was a stay at home mom for 5 years. I started working fulltime in March 2009. I don't have my degree yet still 12 courses away. I'm scared as my husband wants to move into a house in 2010. I want to but am afraid of the huge commitment and I know that I don't have my degree and solid employment. We argue about money living in this apartment. I just feel he can't handle anymore responsibility. My aunt thinks I should leave him as we aren't growing and the relationship has been volatile at times. My kids love him but sometimes I get very unhappy and feel alone in this marriage. He has tried several times to buy a house but i haven't been on board as I felt our marriage can't handle more strain. Not really sure what to do.