Cheating....

So my husband has cheated on my once before...nothing physical, just emotional.. He started talking to his childhood best friend/ crush again after she attended our wedding, and a few months later I found out they were having an inappropriate texting/calling relationship... Saying how they want to make love to each other... How he wish he had married her instead etc.... I was so devastated... But I was so in love with him I gave him Another chance….And he told me he would change and that he would never talk to her again ever… But today I go on our phone site where I can see who he calls and see that he called her three times today... 30 minutes, 15 minutes, then 6 minutes.... he is in the military and he is on a field exercise at the moment and he only gets to call every other day, and he called HER before he called me.... (I saw that he called her after we got off the phone) .. Like I said he is in the field so I can't talk to him until he calls next but I am so ready to leave him... I am so mad I'm shaking.... I don't know what they even talked about but I DONT CARE I'm so mad that he even called her at all because he promised me he would NEVER... That's the only way we could fix this..., And that he would have absolutely NO contact w her anymore.....am I overreacting? Should I wait until he comes home to talk to him?... Idk what to do..... I need advice....