After 4 years, you can't just block and delete. His father died; you yourself said it was a bereavement trip. He has his children with him and it's not a sunny holiday in Granada.
You don't have to wait until he returns to break up, though. Just be the kind person you have been. You can withdraw your support. To do it by a phone call might be traumatic for both of you, to do it by text doesn't seem right either. I'd suggest an email, firm but considerate. Do send a brief text to let him know to look for your email. Explain you've grown apart, that neither of you can be supportive of one another anymore. Say you want to end things now, that dragging it out would make it harder on both of you.
You don't want to give him false hope, so tell him you won't change your mind. Do not leave things open-ended, either. If he has anything left at yours, arrange to send it back to him. If you can return his things safely now, then do that, so you don't need to meet.
Just tell him you are cutting contact; if he needs to get in touch, use email you as you won't be taking calls or texts.
Say whatever you need to, but try not to blame him. If you are respectful, hopefully, he'll be the same.
Are he and his children with other friends or family? If so, even better. There will be things to distract him and he'll have help with the children. Maybe someone to comfort him if he needs it.
Ending things with a block and delete would be so unkind, especially now. Be considerate and think of how you'd want someone to break up with you. If you leave email as the only way to contact you, you can respond when you're ready and if he becomes angry and unpleasant, you have the option to block him completely.
Good luck.