My Spouse's Ex Is A Pain!

I have been dealing with this for quite some time now. My spouse's ex is a pain in the butt. When we began dating in 2003 everything was wonderful. He told me he had a daughter and that his "friend" was helping him raise her. I was okay with that. Well, little didI know the so called friend was really his ex and not his daughter's biological mother. I began to become suspicious of this so called friend. In 2005, I became pregnant with our first child. I was so excited. Here is where the relationship began to fall apart for me. It was at this time he decided that he was going to help her get a car. He discussed it with everyone but me. I felt betrayed and til this day, I feel betrayed. He doesn't believe that he did anything wrong. He says that he didit because the car was not safe for his daughter. Did I forget to mention she is a physcian. Everytime he needs something she is the go to girl for it. When he needs to go out of town on business trips or church functions, rather than drive himself to the airport or catch a cab, he calls her (I was unavailable due to work). Every function wee have had, she was always present. I despise sitting across a table from her. The latest issue is that while he was away at an out of town function, she left a message on his phone that sounded a lot like I luv ya. When I confronted her about this her response was that "its not very descernable as to what is being said." This women ahs caused a severe rift I my family. Then to top it off, he went above and beyond to clear her or at least it seems that way to me. He claims he sent the recording to his brother who put it on a digital machine and it really says I'm out here. If that is the case, why didn't she say that. I'm. At my wits end with this. It is because of this, we are separated at this time. I'm pissed off because my son will now be a statistic because his father can't set boundaries. Can anyone give me some insight on this problem.