If it were me, I would stay put where you are at.. Coming out of rehab back into reality is a very drastic adjustment for people.. And just because he's out of rehab doesn't mean that he won't relapse next week or next month and if that happens its not going to matter if you are living there or not.. Rehabs don't get people clean, they just give them the tools and its up to the individual to use those tools..
You say you can easily find a job? But can you? The economy is still really tough out there and you may not easily find one like you think you will..
Stay where your at, focus on YOU and your recovery.. Giving your finance a little distance in the beginning stages of his recovery by living several hours away will be good for him and you... It will give you the opportunity to desperate yourself from his addictions and him the opportunity to focus solely on his recovery.. If you didn't live with him before I wouldn't suggest it now, moving in together is a huge adjustment in itself..