***AM I BEING A *****? please help****?

my boyfriend and his ex girlfriend's familys are always hanging out together and i dont like it. she still likes him and everyone (including him) knows it. he had his first kiss with her and they are still friends. she sees him WAY more than i do. they are going to school together next year and im going to be somewhere else. i am worried. i trust him but he never tells me when she does stuff to come between me and him. for example : this morning she showed up at his doorstep and said i love you. and i had to find this out from his brother.so i got mad at him. was it wrong of me to be super pissed at him? she always does this kind of stuff and sometimes i find myself talkin smack about her to him even though they are friends. i beat her *** once because she came onto him one too many times. is this wrong? and should i be worried. please speak your mind. and is it time to let him go?