Divorce Support Forums: struggles

I have been married 8 years. My husband and I met his last year of med school and have 1.5 years left of fellowship before he finishs. It has been a long 8 years..struggles financially with 2 small children. I have worked full time the entire marraige and 2 years ago found out that he was having an one year affair with a nurse. We went through conciling and I decided to stay and work things out. We moved 17 hours away from family to finish fellowship and it has been really hard. He is never at home and I still habor a ton of resentment due to the afair. I am jsut sooo unhappy this far away from home and wondering if I am jsut here so the kids are here when he does come home?? I feel stronger each day that we should just separate so I can move back home with the kids. My question is what are the positives of having legally separated and what are my chances of getting any alimony for supporting us through residency when I know in 2 years he will be making triple what I make.