As MEATLOAF says in PARADISE BY THE DASHBOARD LIGHTS --
STOP RIGHT THERE!!!!
First you need to know if they guy still believes the JW stuff. If he does, get the hell outta there!
Some people are DFd because they find out it is really NOT "The Truth".
Other people are DFd because they simply cannot live by the JW Rules. (ie, no pre-marital sex). If he is this latter case, then he will marry you and go right back to the JW Cult (now being to have sex with a wife and live by "their rules"). He will likely expect you to convert. (After all, JW's have The Truth!) He will expect (and be expected) to raise any children as JW's. Your children will be denied higher education and will be expected to sell WT literature door-to-door. He will refuse to approve of you or your children having a blood transfusion in a life threatening situation.
I don't think you know what you are getting into here yet. You need to have a sit-down and serious discussion.
YOU need to learn more about JW's before that sit down so you can ask pertinent questions. JW's are NOT just another protestant religion that happens to be a little "strange". JW's are a Cult. They are about "control". If he is married to a non-JW, he will always be a 2nd Class JW.
Good luck!
Doc