breaking up, s/he might think there’s a chance of the two of you getting back together and incessantly call you asking to “just go get lunch” or “just see a movie as friends” which are not traps you want to fall into.
as far as speaking with them in the weeks following the break-up, it’s probably not a good idea. i advise against pretty much any interaction for at least a couple weeks, and if after those couple weeks you decide that you want to be friends, it’s much easier to sort out both of your emotions at that time. one or both of you will probably be very emotional immediately 