Your gift was very thoughtful! One of my friends recently lost her job and gave me something small for Christmas. It was the thought that count and it was very special to me.
I think it is perfectly okay that you didn't give her your present! If it means something to you, and you like it, and you already have another gift for your friend, there is aboslutely nothing wrong with keeping your present.
It will NOT be wrong of you to use the lotions your grandma got you for yourself! She wasn't giving them to your friend, she gave them to you.
Don't feel like a total jerk. The guilt you're feeling isn't from God, it's from the devil. He loves to tell these little lies to bring you down; especially when you're already struggling with depression.
Go ahead and use your present for yourself and give your friend her present.
There's nothing wrong with what you did.