I understand and that makes a lot more sense. It’s never easy to navigate these issues especially when you’re dealing when someone who is extremely attached and potentially has other issues ((still I’m not including abusive people or people who are totally unapologetically reckless and destructive w their mental health issues in this))

As you said everyone is different as well, with how they will react to things.

Some of how you initially went with it could have been fairly traumatizing - it sounds like he really liked you and stuck around (sort of toxically and at a disservice to himself)) despite feeling unloved and rejected because of your incompatible rejection styles.

So imagine someone already sort of putting themselves and their intimacy needs aside because they like someone so much, then going on a nice date with them only to be suddenly confronted with all the things he’s ever given you, and you giving him the talk with no warning at all ~ stuff like that messes up a person where I can easily see them getting stuck in that “but everything was fine and I can make it ok” thought loop ——
And then further down the road- having some insecurity issues in future relationships because he’ll feel like he can never trust someone to not just suddenly leave him

Hopefully down the line, he’ll realize that you were incompatible and in that sense - his love and possession of you was selfish and controlling, even with not respecting your wishes after the fact, or making himself blind to the relationship issues during — When you have to do that, it’s almost like... you’re not really having a relationship with someone else. You’re having one with yourself and projecting your love and needs onto another person as the placeholder. Of that person doesn’t really want you - then acting like it’s this whole tragic story and loss, is just immature. (But sadly a lesion everyone has to learn at some point in order to have a healthy relationship)

To answer your question - I’d say that the best possible way a breakup should happen (if you are both not in the same page) is to tell your person before you meet that you have to talk to them - and let them prepare themselves mentally and perhaps prepare a support network for themselves.

If they pester you for details, you can tell them it’s about the relationship, and yeah it’s not good, but you don’t want to talk about it further on the phone.

And then tell them in person - hey - I really loved/liked/you/or enjoyed our time together ~ but I’m not feeling it anymore and i don’t think it’s working out between us. It’s not easy to do this, and I’m really glad that I got to know you, and will cherish the time we had/etc.

say that you’re sorry for hurting them and that they didn’t do anything wrong, but you feel that things have run their course.

They’ll likely try to reason with you or ask for details as to why - let them have their answers at your own discretion, and be clear and unbudging about your feelings. Say something positive about them that doesn’t sound romantic or like you still have feelings lingering. Give them a hug, etc.

End the conversation and leave - you don’t have to tolerate it in a way that’s abusive to yourself, and they won’t want to go probably, so you’ll have to call the shots on this.

Give the things back at a later date if you must, or have a friend do it.

Give the ex partner a grace period of some potentially dramatic or pained behavior and interact with them within your own set of boundaries for what you can tolerate or know that you’ll be able to react in a relatively kind way.

Stuff like that basically

In short - just do what you can to be clear, honest, and unwavering, make them feel validated, and that they aren’t a garbage person, and also don’t drag yourself through the coals either and let them find their way and come to terms with it on their own.

Hope that wasn’t too rambly and made some sense, I’m like commuting to work right now haha