Hi,
I’m so sorry to hear you are going through this!
I personally do not think it’s unreasonable at all to expect honesty from a partner when someone is dishonest we feel very betrayed.
I’m glad you have approached this topic with him. It’s in his hands now to be honest with you. He cant paint this relationship with the same brush as his previous ones . You are entitled to have a boundary around this so my only advice would be to remain firm with him.
Xx