Agony,

All of this putting a lot of pressure on your fragile marriage.
For the sake of your marriage and your peace of mind you need to clear house of relatives. It is a good start with your Mom being gone now. Don't let her back in and it is good that your Aunt finds a different place to reside.

Mom is acting like a love struck or immature person in this relationship with her boyfriend. She is with a man that controls and doesn't like kids. That is a recipe for disaster.
Don't be surprised if one day she finds out the hard way what this guy is really all about. I'm a little amased that she would even get into a situation like this. The one I feel sorry for is the 8 year old. This will have a hugh impact on his outlook in life.

You are absolutely right in putting your family and the preservation of your marriage first. It is too bad that you were taken advantage of like this and having to learn a hard lesson.

Hang in there and do your best to make it work.

Good luck,