it sounds to me like you can't simply be his freind right now...which is OK by the way

hoping to show him how great youa re
or proving how much better he is with you
or praying that he will be more than friends with you again

is NOT no expectations

no expectations means just that


if you can not be this
then do not try right now

revisit the option later when you have let go more

it is not vital for you to be friends with him

sometimes they are people we would not ever want as friends

pray for him
that he finds his way to happiness
wherever that is
true happiness

and
be a friend to yourself

don't push yourself to be someone you are not
you do not need to martyr yourself in order to be his friend

perhaps the most loving thing is to not be his friend, to not enable his choices, to prove to yourself that you are more important than how he is treating you, to impart this lesson on to your child

perhaps the most loving thing to do, since you can not be his friend with no expectations is to not be his friend...not that I am saying be cruel to him
i am saying pray for him
and
keep your distance for you and for him and for your son

keep your emotional distance so he doesn't feel the pressure of always letting you down by not giving you want you want
so that you don't always feel let down and hurt that he can't see how amazing you are
so your son sees what an emotionally strong person looks like