Do i have the right to be upset with ex-boyfriend lying to me about taking another girl on vacation?

we broke up 3 months ago. we were in a 1.5 year relationship according to him, 2-3 weeks after we broke he arranges to go on vacation with a "girl- friend" alone to a lovely urban getaway to london. they shared the same bedroom in a hotel (two separate beds he claims) etc. in between the 3 months it seemed he still wanted to reconcile with me and doesn't tell me about the friend. you see we were on speaking terms and he lied and said that he was going alone to london to get away from things and people BY HIMSELF. when he came back from london he confessed that he went with a "girl friend" and didn't want to tell me because he was afraid of how i may feel? so what changed? all of the sudden i had to be informed. of course i asked him questions. i never met the girl. they had kwown each other for 3 years and in the beginning when they first met he thought maybe she would be a romantic potential. he said they didn't do anything? that this woman was an high integrity woman and a woman that would not have sex before marriage. if she was so high integrity and virtuous woman, why would she go on vacation with a "male friend" alone sharing a bedroom on vacation (especially with a friend who was having problems with their girlfriend)? i asked him if he told her if we were broken up. he said yes he told her that we were broken up. and in a later story (a couple days after he came back and after the confession) he tells me that he didn't tell her that we broke up and that she told her that we were having problems? the story changes. i pointed out to him. he reasoned. he may have told her both. maybe one time he had broken up with me and another day that he may have told her we were not broken up and that we were having problems. doesn't that seen convenient for him? he thought that the change of story was minor. the main point was nothing had happened especially with this particular friend. why would a friend, a supposedly "32 yr old virgin" woman go on vacay with a male friend that was having problems with his girlfriend. i told him that didn't make sense to me. he said..yes it would not make sense to me. why didn't he tell me the beginning that he was going to london with a girl. and why was the stupid one (in a reconciling mode) we were not quite together just chatting and talking about getting back togther) waiting at home expecting his text, email. which was rare. I even ASKED him too are you going alone or on a tour? before he left. he said he was going ALONE. and now he is back from his vacation and said he had to tell me about the girl. and because i wasn't receptive with that info. he then said he didn't have to tell me. and because i am furious and accusatory that he feel now he shouldnt have told me. that's worst right?!. i dont think im over reacting. he did lie about going alone and if this was so innocent..doesn't that negate the innocent. we were in reconcile mode...but this is too much. i can't believe he told he that he didn't owe me an explaination. yes, we were broken up and what ever he does is fair game. but we were in reconciling mode 3 weeks before he left. he had lots of opportunity to tell me. i told him he wanted his cake and eat it too. that he wanted both. he said he was afraid to tell me because he knew it would look bad. and that i would not see it as innocent. he said it was a lose-lose situation. and now...he tells me after he comes back. i think that say allot about his character. he was afraid to face the music in the begginng and decided to have "fun" before reconciling with me. and i assume he feels guilty so he had to tell me after the fact he came back. i was the one here waiting for him and he had this other "virtuous" 32 yr old virgin in his hotel room. honestly its hard to believe!