Secret snapchat

I caught my husband creating a secret Snapchat on Friday. He had previously been unfaithful however I gave him a chance 4 years ago and he’s been an amazing husband since that incident 4 years ago. That why I don’t understand why this happened! I said last time I would never tolerate it again, I just don’t know what the hell to do, he’s going to start therapy and booked his first session. I just feel like I’m between a rock and a hard place! I should stand by him whilst he does the work to fix himself but I’m just kinda repulsed and can’t trust him.