is there any chance of fixing this marrage

i recantly separated from my wife in june .i needed to clear my head i wasnt happy with my life. i wanted more kids she did not. she moved out started a new job and her new life.we agreed to make a clean slate and start over. in sept. she goes on a date with a guy (our anniversery date) and come to find out she went all the way with him and i mean everything incuded .she made me wait 18 months til marrage and gives it up to him in no time at all.now three weeks in to there relationship she wont call him a b.f. it seems more like freinds with benifits to me witch makes it worse.should i just close the book on this and move on or wait and try to get her back. my biggest problem is i cant get past the facts of she told me they have done.she always said sex is very intamate and oral even more so.i was the only one.now she says its only sex its only a bj whats the big deal should i feel betrayed or thank my lucky stars and get out now.