I'm sorry. It sounds like you're in a pretty rough spot. I gotta be honest here. How long have your bf and his wife been poly? Your situation reminds me a lot of how my wife and I were at the start. It almost seems as if she's jealous and really only wants to be poly and have your bf be mono to just her. But she knows that if she wants to be poly then she has to be able to let him be as well. "Only fair" kinda thing, you know what I mean?
I agree that you have to be more assertive with what you want. I know that you love and care for your bf, but this lifestyle isn't for everyone. I'm not sure they really discussed bringing you into the picture. You mentioned that he even lied about something at the start. There can be NO lying if this relationship is going to work. You also have to be fair to yourself. You're not happy. You deserve to be happy, but I hope you don't need me to tell you that.
Talk, talk talk. That is my mantra when it comes to being poly. My wives and I know that we have to talk about ANYTHING that might be on any one of our minds. We also know that those conversations aren't always nice and pretty. But they're necessary. (I'm pretty sure I posted this somewhere else too...lol) I hope that everything works out for you and you end up happy. By whatever means that's supposed to happen.
Live life to the fullest 'cause you never know if you're gonna wake up tomorrow!