Oh OP, this must be so hard.
Im not sure how cryptic you want to be on this thread. I'll try.
Firstly, you are allowed to talk about the nature of your relationship, and that something was very wrong. You don't need to be specific, you don't need him to confess or even acknowledge it. But something like 'we both know there are important reasons that our relationship would never have worked out'.
Secondly, you can say that you never wanted to be a SP, or in a CoP situation. Once you realised that these were the only opportunities available to you, you have to do what's best for you. It is very sad. But you need to resolve things and look to the future.
Try approaching it in this gentle way to begin with. If he kicks off or tries to make you feel bad - cut him dead, block him, no contact, research advice around harassment.
I really feel for you. But you are not the cause of this, his problems with lying to himself and using you are the cause of this. If he really wants something like this there are many many routes for him to achieve this. Without wrecking someone else's life in the process.