the case of the ex...

I would kindly tell my guy that I was not comfortable with it and would ask him to stop or at least keep it to a minimum. If he persists I would give him a taste of his own medecine!!

It would not bother me as long as there is a fine line between just friends/keeping in touch and flirting/hooking up. Because in some case, couples were friends first before they hook up so if the break up was amicable, most likely, the freindship would remain. However, if either party is still not over the ex (or worst, would want to get get the ex back), then it would be very disturbing to have my partner still contacting the ex.