In-laws never include me in anything?

I have been married for 3 years and from day one my in-laws have never included me in anything. My husband is in the military and we live 4 hours away from them and every time we go home they always offer to take him out to eat and go shopping with him and i'm left alone. Im also 4 months pregnant and his mother thinks she is gonna take my baby to go visit her family in another country and when I tell her no she gets all mad and defensive. They are renewing their vows and having a huge ceremony this weekend and I am not in it at all. My husband is walking down the aisle with his sister and cousins and I have to sit just like everyone else. I also have to drive myself to the church and the reception while my husband and everyone else in their family gets to ride in a limo. His mom also told me and my hubby 2 months ago that she was gonna buy my dress and that we were gonna go this past weekend to make sure it was gonna fit since my belly is growing now, and she never did. Didn't mention it at all. So I had to charge it on my credit card. All of the girls are also getting their hair and nails done that day and I know shes not gonna say anything to me about it. I'm having their first grandchild in December and I feel like such an outsider. They speak mostly spanish and I know alot of it but they will talk about me in front of them as if I don't know what they are saying and it really upsets me. My husband knows how I feel and agrees with me but hes a freaking mommas boy and god forbid he ever tell her shes wrong. My parents are also invited but I dont even want them to go because I know they will just be ignored the whole time like I am. I really don't even want to go anymore.