Should I move on or give him another chance?

I would just cut your loses and move on, men have a habit of repeating Old habits. So even though you told him the new rules and stuff, he will probably only try to be more sneaky about his private business.

Lots of fish in the sea

I think you need to talk to him and tell him how your feeling, tell him your concerns. Ask him for reassurance and go with your gut instinct. Me personally if my fiance ever cheated on me it would be over forever, and we have a child together, that line is not to be crossed and she knows it. I don't worry about that though we respect each other and love one another too much. you decided to give him another chance he is lucky, VERY lucky so keep him in check and until you feel better and the trust is restored have him account for his actions, wherabouts, and the places he goes. Due to my career field I trust nearly no one, you can always follow him and see if his stories check up, write the mileage down on his car and see how far he has driven, mapquest it and see if the mileage checks out ..... also you can request a copy of his cell phone records and see if any phone calls incoming or recieved match a culperate. REMEMBER HE CHEATED ON U THEREFORE GLOVES ARE OFF UNTIL U ARE CONFIDENT THE TRUST IS BACK CONFIRM ANY SUSPITIONS, GO WITH YOUR GUTT FEELING IT WILL BE RIGHT ON EVERY TIME..... GOOD LUCK

I agree with Rosynante, great last sentence.

If you have kids, or are going to have one, then you should try and work it out.

I don't know how effective "ground rules" are, after all didn't you have those before, since you were in a relationship?

Best advice is talk to a qualified professional relationship counselor and try and work it out.

Good luck.

Run for the hills! Trust your gut feeling honey! This guy needs a bit of growing up to do

Wow. You are pregnant, damn. Well, this is my advice. If he is being good then you should stay with him and try and help him be a better man. But if he does it again then you should leave him completely.

Gah! You're pregnant? Nice detail to throw in there in the last sentence. :)

I'd say try to stick it out if you have kids involved. If there is any chance it could work, give it your best shot.