Help me save my marriage?

My husband and I have been married for almost 2 years, hes in the military. Weve had alot of marital problems since weve been married but weve always worked thru them. We now have a 13 month old son together. He went on vacation 2 weeks ago by himself back to his hometown for a little get away before his deployment in august, everything was perfect with us before he left but once he got to FL he stopped talking to me completely, I found out hes talking to another woman but says theyre just friends..He now is threatening me with seperation and divorce (wich hes done a million times but never went thru with it) Hes been sleeping at the barracks instead of at our home some nights last night he did stay home with me and even slept in the same bed with me, we still do have sex as well.. Id do anything to save my marriage but what can I do if my husband sayd he doesnt want to be with me? I know my pleading and everything isnt working one bit.. Help!