I FELL for a married Marine co worker and hes leaving for deployment in a month. (he feels the same) what do i do?

You walk away. If you are also in uniform, UCMJ fraternization rules apply. If not, you walk away because he is a married man.

Forget it. Find somebody who's single. Why do you want to screw up somebody's family?

There is no up side if you continue with this, either for you (because he's probably not EVER leaving his wife) or for him because he's subject to UCMJ penalties for adultery under Article 134. By the way, if you're in the military, you could be similarly charged, even if you're single.

I used to see this stuff all the time:
• Married guy feels restless.
• Married guy gloms onto somebody susceptible to his charms.
• Married guy has his fun.
• Married guy decides he's had enough fun and goes back to spouse.
• The "other person" gets screwed, and not in the fun way.

Look, I assume you're an adult, so you can do whatever you want. I'm just telling you that this is NOT a new story.