Of course you can realistically ask that of an ex, especially after 7 years together and with how things ended. However, you can’t realistically expect them to agree.
I find it dubious, though, that she just straight up lost all care for him, despite how she handled this. For all we know, she has a lot to say to him as well. I don’t think there’s anything wrong in seeking closure.
I’m really happy to hear you have someone to talk to. Venting to internet strangers can for sure help, but can’t compare to real life friends who care about you and understand your situation much better. And that’s such a great way to think about the couples therapy proposal; that’s a perspective I didn’t even consider when writing my comment. No matter how you decide to move forward with all of this, I hope your heart heals well. Stay strong!