How we will know that my husband forget his ex wife,pls help me..?

i am married for black american, he is divorce they hav 3 kids, i am a filipina, the 2 kids live with us and the 1 kid live to her mom. but his ex wife calling here at home bec for kids and sometimes she want to talk to my husband, and the kids want to talk also to there mom. her ex hav a bf already they r live in.,, i always keep on jealoues everytime my husband talk to his ex.. they only talk for kids only.. what should i do so that i will not get jeolus,, how we will know that our husband did not give important to his ex everytime she call..help me pls..