What to do if I cheated on my boyfriend once and would never again do it? I cried a lot over this. I want to spend the rest of my life with him.

Hello. Well, I am not aware of the circumstances under which you cheated but relations are based on trust which might have been affected due to this incidence. The situation seems a bit challenging and complicated. You can, maybe, try reflecting on the situations under which all of this happened and your actions and feelings at that moment. You can work on yourself and your resolve and then maybe try connecting with him (in case you are not now). You can slowly work towards gaining the trust and ultimately, leaving the decision on him. I wish you the best.