Don't worry. One lunch won't undo everything you have done. Everyone will make mistakes and after being pushed and pushed even the gentlest dog will bite. You can't expect to be pushed and not at times come back at it. It is ok and he will calm down and be back to normal in no time.
I can't believe H asked to take S to OW's house. Is OW married? If she was that would at least be a little comforting since it is her S's birthday, if not...I don't know what to tell you. Right now I am really dealing with that myself. Luckily H will never ask to take S anywhere himself. I ALWAYS initiate the visits, unless it is a doctor's appointment. If not for me initiating it, H would not see S. It completely sucks and sorry to say I don't have any positive thoughts here.
I hope S starts to feel better, and that you feel a little better later. H probably was trying to get into a fight because he hates that you set a boundary on the sex. I am proud of you for that, but he is responding to the new boundary and will get over it. He probably just wants to make you jealous because of the boundary. Don't take anything personal. You did the right thing. Yeah...it stinks that you gave in to the fight, but like I said above, you can only go so long.
Give it a few days, he will calm down.
Me29 S3 H left 4/1/09 I file 8/2/10 Divorce final 5/17/11 1st http://www.tinyurl.com/25lhu52 2nd http://www.tinyurl.com/2c35ueg 3rd http://www.tinyurl.com/322yk89