PLEASE help!! boyfriend problems?!?

(Sorry its long) My boyfriend was off on vacation with his boss/cousin in Mexico. I was on facebook and seen that he was all of the sudden single. (I'm am promised to him...) And he said his little cousin did it because he didn't log out on his phone. He said his little cousin wanted him to get with a girl that was there with another family they were hanging out with. He told me she flirted with him after I confronted him about the facebook deal. I was pretty angry because if it was the other way around he would be flipping out on me. He told me one more sign of distrust in him and the facebook thing stays the way it is. He knows I have trust issues and I told him so. He gets mad because guys text me and he thinks I text them when I don't. He told me he's tired of fighting for me (even though I tell these guys not to text me) and if he found out I was talking to them it would be over. After I told him I'm sorry and I try to be perfect and he says baby you are but then precedes to say he believes it would take a few days to replace him. I do love him with all my heart and won't replace him... I just don't know what to say or do... Any help would be great.