Ethan:
I am sorry to hear that you are going through this. Even though I have never gotten a divorce and my parents are still married, I practiced family law exclusively for 6 years and I saw so much crap that it is amazing I still believe in marriage.
A few thoughts:
No matter whether someone is 18 months old or 18 years old, it will affect you. It is important for your sake that you allow yourself to FEEL the range of emotions that you have so you can process them and come out the other side. The worst thing is to deny it is happening or refuse to acknowledge how crappy you feel (the "I am fine" syndrome). There are no winners in these cases. Everyone loses. Mom won't understand your feelings because she has her own feelings that are different than your feelings. The same with dad. All you can do is take care of you. Really.
I saw people who used the kids to destroy each other and I had to participate in that as a part of my job. Now, what I can say is that most of the time I stayed involved BECAUSE of the kids; someone there had to look out for them. Sometimes, I handled these cases, even though the client/parent couldn't pay me, just because someone needed to try to intervene for the kids sake. By 2005, I needed to step away from the mess of practicing family law and have transitioned into teaching law now, which is a completely fullfilling job.
The way that I got through dealing with these situations, as difficult as they were, was to keep in mind that it is never good for parents to stay together if the relationship is really dysfunctional. It hurts everyone involved, especially the kids, to see the fighting and nastiness and hatred between two parents. The situation is emotionally toxic and can affect the ability of kids to find emotinally healthy relationships of their own. When all they see as a role model are people fighting and being verbally/emotionally abusive to each other, they will feel a strange sort of "normalness" with relationships like that, and will seek out that "normalness" in their own adult relationships.
Sorry for all the psychological "advice"; I don't mean to make it sound easy or smooth. I am just trying to give some rationality to the situation, if that is even possible.
You will be in my thoughts.