I'm with Mike, you definitely will be walking on eggs if his getting sober is to get you back. Puts you in a bad spot being responsible for his drinking (or not). Besides, if he is intent on proposing so soon into your relationship *(less than one year together, right?) that, coupled with the abuse (which tends to escalate over time) you paint a very "codependent"budding relationship. Red flags are waving.
If you decide to take it on, my advice is to take things slow. If you are uncertain, I would suggest you take the time and read about addiction, codependency, al-anon. Take advantage of the tools available on SR. Good luck to you.