I’m scared to tell my husband I had an affair and am afraid it will hurt him a lot. But I feel like I have no choice because the man I cheated with told me if I don’t say anything he will. What to do?

I completely understand that you are scared, it's very natural in your situation to be fearful. It is very likely to hurt him a lot but honesty is really important in a relationship and it's better coming from you than the man you cheated with. Make sure you pick a time to tell him when neither of you are busy and you won't be disturbed. Warn him beforehand by telling him you need to have a conversation that may be difficult. Be honest and take responsibility while being apologetic and calm. Be empathetic and talk things through. I hope everything turns out okay!