1. You will eventually get over him just give it time, lots of time if you need it. It will take as long as it takes.
Think of the sadness as something temporary like a cold or a sore muscle. Yes it is uncomfortable but eventually it will go away so no need to obcess over it.
2. He used you for his own selfish needs then moved on. JWs are no different than any other people in that regard maybe even more so.
You said "I have lot of respect for his faith"
Don't, if he was really acting on that fath he would never have gotten involved with you in the first place.
He lied you on and you have the right to be mad at him for that.