Hi Sstupi,
Thats sad that your Dad doesn't put you first, I'm not sure what the situation is that there has to be sides, but it must be a hard position for him to be in though.
I don't think there is really anything you can do other than just accept the way things are as we can't change people, and If you want him in your life I think thats the way it will have to be as hard as it is!