I don't know how to feel about my dad cheating on my mom and I still feel very uncomfortable.
How much do you know about what is going on between your dad and mom?
I'm not sure but my mom is very unhappy with the situation.
Children should not get involved in their parents relationships. These are not problems you should have to take on.
I want to make my mom happy.
While I have to reiterate that you really shouldn't concern yourself with your parents' marriage, I find your concern for your mother to be laudable.  This is a difficult time for her, and anything you can do to help will be greatly appreciated.