I’m a cheater

I been in a relationship with my boyfriend for 2 years and I have never cheated . But this morning .. I have , I feel so guilty so broken .. me and my boyfriend been having some issues after the birth of son , I moved back in with my mother and he did to , we only seen each other 2 times in the past 2 months because of the distance . I love him , I want to be with him and work on us . But I don’t know how I am going to tell him I cheated .. it was a mistake . We had a fight the night before and he told me he didn’t love me anymore . I needed a distraction. Something to help me with all this pain I have . I am 18 , I work full time and I now take care of or son alone ( not financially alone) . I feel so terrible . I came here to get it out . I can’t keep holding it in , it’s breaking me