If a guy left you and decided to come back would you let him in?

So my ex left me, months ago around August and it wasn’t really bitter from his end it was mainly me getting angry with the fact that he left and never told me why. I feel like I dealt with it in the worst way and wish I could of taken it back and just been more calm instead of showing him I was mad over it. I’ve realised that now, so I do know that there could be a small chance of him coming back and a part of me would rather not let them back in because they chose to leave when they did but also I should be respectful and let them back just to be civil and maybe even apologise for the way I acted? Obviously nothing could also happen it’s just a thought that there could be a chance they did come back.

The relationship it’s self wasn’t really toxic it’s just we both wasn’t ready and maybe there is such a thing as it wasn’t the right time for us since we was at different life stages. So I sort of understand it now and I feel i can sort of get why he might of left because he didn’t want to hurt me by staying when it wasn’t going to work out anyway. This is all just me overthinking but I need advice if there does come a time where he might decide to come back and what would be the best option to do because I don’t want to act bitter towards them or having hatred.