Relationship advice

Ok I want to know if what I done is wrong what others think cause I feel terrible anyway me and my boyfriend of several years broke up and within a week I went out with a guy and we had sex well now I'm back with the guy I was with for several years and not sure if I'm pregnat or not I really hope I'm not because it would hurt him so bad because we have been trying to have a kid for little bit now and not had any luck anyway am I a bad person should I feel bad and he don't know I can't tell him..