My husband admitted to speaking to his ex?

There is no trust now. But you have a baby, so you need to give him a 2nd chance, you don't know if he did anything more than talk to her. Were you aware of this "rough patch"? That would make me feel so humiliated, I don't know if I could forgive him. Even if the number is not on the bill next month, what if he used his work phone or something? These are going to be questions in your mind, you have to be really sure you can let it go or there will always be problems.