Advice feed back please... Dont just look please leave advice thank you

Soo me and my now ex boyfriend had broke up.. He broke up with me last Saturday over something small and meaningless and now after some days went by of me being hurt I been focused on working out and taken care if my kids and my new Job.... He hits me up like I know your talking to someone else... Smh when I'm not, im fucking heart broken and this is all he can come up with... Smh he doesn't get it... I done tried and tried to work things out with him but all I get is a dead end Smh can someone please tell me why is he assuming these type of things...