NO ultimatums...

they don't work or really exist...
if you are trying to say to them someone else..

ultimatums are internal deal breakers..

he or she has the right to choose to do this or that...
but if they choose this...
I will do ____________
and
if they do that
I will do ______________

You've already told him you need him to not be in contact and he told you...

ummmmmm that's what happens when OP live in a different country...

what exactly would your ultumatum look like...

you KNOW he is going to keep contacting her...

ARK