When couples split up, there is rarely a simple split, end of contact, end of thoughts, job done - that only happens in soaps where one party gets in a black cab and drives of to panto land.
Here in real life, things are never that simple.
If you have contact with your ex, either or both of you are going to be scratching off the scabs of the wounds that split you up in the first place.
This becomes a minefield of - what did this sentence / reaction / kiss / phone-call mean? And round you go, messing with your heads, and it is no good for either of you.
If you are going to move from 'ex's' to genuine friends, where each knows where the lines are, and does not cross them, then the best thing is to have a clean break for a few months with no contact at all.
When everyone can think straight, you can work out what each of you want, and decide if both of you can be friends.
If one wants more than the other is prepared to give, then friendship is not going to happen, and that is when you stop all contact completely - it's the only way to avoid messing up your life in the future.
The notion of a friendship with someone you were once in love with sounds like a great idea - adult, civilised, remembering all the good times, and so on.
But it is not that easy, and you have to be prepared, and willing, to let this man go for both your sakes.
Start with a prolonged gap with no contact. If friendship is going to be an option, this will do no harm. If you or he is fretting, then it is not friendship you or he want, and that is the time to re-assess things.
Be clear-headed, be adult, and don't pine for something that is not going to be there if this doesn't work, and from his actions, it's not looking hopeful for a mature friendship for the two of you.
Give it a chance, so you know you tried, but be realistic, and be fair to you and to him - it may be time to put this into the memory bank, and move on.