Very down again today

The worst thing about this thng is the rollercoaster feelings.one miniute im ok then my mood just plummets and all i want to do is sob.He text me last night asking if i was ok and i know i shouldnt have text back but i did,then he asked if i minded him texting me and said he knows i prob dont want to hear it but he does think of me.He went to pick up his kids today so he must have seen the ex and its killing me wondering whats going on (did they fall into each others arms and get back together).Of course ive heard nothing from him today what did i expect?He dosent want me he wants her.Why am i allowing him to play with my feelings like this?