Ingot my self in a sticky situation that i regret !

Shey guy i really need addvice no judgment im not going to plead my case im going to get right to the point . so i been with my babyfather 5 years and he put me through so much . i whined up leaveing him and i met someone else we was talking for about 2 months but then i whined up messing around with my babyfather and now im pregnant and idk whos the father and the guy im with now is a great person amd he thinks hes about to have his first kid and its killing me inside because its a chance its not his . how do i go about this what do i do, i dont wanna lose him i finally have someone who really makes me happy , but i refuse to keep him in the dark about the situation.