Opinions plz

I'm February 2015 my husband and I was pregnant with our second child and he made a mistake and cheated the first time in six years he said it was only a one time thing and that he knew he messed up and he was deeply sorry but the girl said it was a number of times idk what to believe but I do feel that he is very sorry and that it was just a mid life crises we been married since we was 18 and I cheated in the beginning so I don't believe once a cheater always a cheater . he always goes out of his way to provide for us and make us happy . so I'm asking opinions about am I the only one who don't believe once a cheater always a cheater ?