It sounds like you might be feeling low because of the stress in your home. I think most people in your shoes would feel bad.
We shouldn't have to choose between parents but it isn't uncommon from what I've seen that kids feel they are being forced to choose.
What kind of diet do you have? Sometimes how often or what types of food we eat can help us overcome feeling depressed or sad. Also, exercise can also help because it gets chemicals moving in our body and helps perk us up.
Lots of people don't really want to know what is hurting us in life. They act all nice or helpful at work/school/church, etc, but if you try to confide in them they seem like they can't get out of there fast enough or they start to treat you weird. I can understand how you might feel that way. Is there a school counselor or someone at church if you go to one that counsels? Sometimes pastors also are counselors and they are often a good ear and don't treat you like scum when you confide in them.
Even if your parents feel you do complicate their lives, you are their child and that is part of the package. Every child under the sun complicates the lives of their parents for as long as they have any relationship or live at home. You are a wonderful complication, I promise!
If their view is so short sighted that they don't see past their personal squabbles and dislike of one another they need to straighten out themselves first, maybe. That is NOT YOUR FAULT!!! You seem like a wonderful young person who should be cherished and not left to feel all alone fighting against parents who are acting immature.