Simon, listen to Always. You can't do it all the time all by yourself.

Have you ever flown, or have you heard the instructions given by flight attendants. They say, in case of an emergency and the oxygen masks fall, to put it on yourself FIRST so you can then help others. If you don't, you'll pass out right away. It's the same with everything else, especially emotional help. YOU need to take care of YOURSELF first before you can help your dad. You need time for yourself to recoup, to fill up your own tank as it were. How are you going to help others if you're running on empty? You can't. It's not bad nor selfish. It's necessary! No need for guilt because YOU need whatever it takes to keep you running in top condition, ok?