Sorry Doesn’t Fix Infidelity
The word sorry doesn’t fix all things. It lets others know that you regret your actions, but it doesn’t take away the reality that you committed those actions in the first place. This is an important thing to remember since many of us think the word sorry erases the past.
It’s pretty clear from the OP’s perspective that apologies don’t mean a thing to him, especially when his ex-girlfriend readily jumped on someone else’s Twinkie in their own apartment. You made your bed, now lie in it, lady. Even if you’ve been saying sorry for three years, it doesn’t change the fact that you cheated.