SA partner won’t tell me the last time he cheated

I recently asked my SA partner which date he is using as means for the start of his “sobriety,” which basically is asking when was the last time he reached out to a SW or cheated. He told me that he’s using the day I found out about his addiction and the day he finally admitted he had a problem as the start. To me, I don’t think this is fair to use because it’s not the actual last time he cheated. I want to know the last time he did it and count his sobriety from that day but he refuses to tell me because he said it wouldn’t change anything and that he already has been truthful about his cheating and addiction. Said that his therapist said choosing the day he finally came to terms to his addiction is perfectly fine, but to me, it feels like he’s still withholding information from me, and by default is still lying.

Dday was back in September 2025, we have been dating since June 2022. His last review from a SW on Mr. Number was on Nov 2024. As far as I can tell, he definitely still reached out to hookers between that last review and when we discovered his addiction. Is me asking for an exact date valid for me in terms of knowing when he last cheated on me in order to help me move forward in trusting him again? I feel like him withholding this information keeps me from trusting him bc he’s still hiding the truth.

Not sure if I’m asking for too much. We both are in individual therapy and in couples therapy. He has been putting in a lot of effort to beat this addiction and told me he has not reached out to anyone since the discovery. I just can’t get past wanting to know the last time.