I once found a tiny, tiny bit of fuzz behind my tension spring in my bobbin case that caused thread breaks for me. It drove me nuts because I didn't see it at first because it was so small. You might also check the bobbin case where the thread comes off the bobbin through and up through the hole in the bobbin case. That little area that looks like its metal on metal can get a little iota of fuzz packed in it and that will cause thread breaks as well. I know this all started for you with a broken needle, but it may have been something in the bobbin case that caused your thread to bind, flex the needle and cause it to snap.