Boyfriend's ex & His family

Madison
Me and my boyfriend will be together 2 years in January and his mom and his sister in law still can't leave his ex in the past! This pisses me off too no end. Not to mention when we first got together his family, especially his mom always talked about her. And now recently his sister in law invites her over to their house more and more. First, it was too her wedding, where she was a brides maid. Next, too help her move back into her in laws house. Lastly she's been invited to their house multiple times 
(& the only way I found out was when the sister in law post pictures on Instagram). That is completely disrespectful to me and my boyfriend. His mother wouldn't allow/do that to her other 2 sons and their wives. So why me? I've been nothing but respectful to them over the almost 2 years. So how do I handle this? What my boyfriend has said to them clearly went in one ear and out the other..  It pisses him off & and it even pisses me off more when neither of them can be women enough to my face and say what they got too say?