5 weeks prego but dont think its my boyfriends help asap thank you9

Im 5 weeks prego but dont know if my boyfriend the daddy. We have been trying for a year and nothing till now.... BUT i cheated on him 2 weeks ago... its not possible if i took a test saying that im 3+ weeks prego right?!! thats its not my boyfriends? i need answers please. I really want kids but i made a mistake cheating on him i just find it hard that we try for a year like we have sex like 2 times a week and then we prego all of a sudden, or could it be the guys that i cheated with ? Like i was giving up trying with my boyfriend because i thought i couldnt have them or he couldnt ... so question is... is it possible the baby not my boyfriends they guy i cheated with did not use a condom and never went in me we dint have sex just like he would put his penis around the area but he never went in and he would cum like on my ass but his pre cum i could feel on my vigina and asshole like we was messing around but he never stuck it in sooooo the chances of that being his kid is what?? Thank you sorry im a bad person....