Boyfriend lied

Last month my boyfriends future sister in law told my mom that he wanted to leave me and he wasn’t interested in me. (She is a drama starter) so at first I didn’t believe he said it but than I did. I pulled up to his house and I asked him “if you don’t want to be with me tell me right now.” He said “ babe I promise I love you I’m in to you idk why she is lying I wouldn’t say that.” A month went by this whole time I’ve been hating his sister in law. I decide let’s play honesty hour. He admitted he did say that but he doesn’t feel that way anymore. I’m hurt I’m fustrated I’m angry. I needed to vent. Sorry for a long post. Hope everyone’s day is better than mine.