My BF was arrested this past July and he plead out to a misdemeanor, he is an illegal immigrant without inspection and is now in removal proceedings. He is married in his country so I think is would be better that he goes back gets divorced and then I marry him. What are the chances that he can come back to the us?

He can not of course ever marry you till he gets a divorce.
His criminal record will hurt his coming back. He will need a immigration attorney in the US

My BF was arrested this past July and he plead out to a misdemeanor, he is an illegal immigrant without inspection and is now in removal proceedings. He is married in his country so I think is would be better that he goes back gets divorced and then I marry him. What are the chances that he can come back to the us?

First of all, he needs to return to his home country and get divorce. Since he entered US without inspection, he must leave US and return on proper visa only. Please note that bigamy is one on immigration's prohibited list so you should not rush. It's best to leave this gap at least 12-18 months before you apply immigrant visa for him. Keep record of all communication between this waiting period so you can prove your relationship is genuine. If you proceed too quickly, USCIS might look at your relationship as marriage for convenience and it may lead to more difficulties.

You would also need an experienced immigration attorney to file a waiver for him.. this is not easy and not cheap either.