Am I being ridiculous?

No you're not being ridiculous.Your father most likely doesn't expect you to be thinking about him every second of every day. If you are feeling very stressed out about the situation with you friend i would go and talk to her about it. If you think she'll be hurt about the guy who do you value more? The guy or your friend? If it's the guy then shoot for the guy forget about your friend. If it's the friend and you should just drop the guy and focus on your friend for now. Because you're going to go through tons of guys in your life, but if this friendship is that valuable, you don't want to lose it. I would approach your friend, not about the guy, but about the other drama going on. You aren't going to be able to fix your friendship without her help. I hope this helped. And my best wishes towards your father. Hope he gets well!