I pulled a few cards for you and this is how I see it:
Six of Cups
I believe the first card is referring to nostalgic memories of your brother. After all, this is his birthday coming up and it seems if the plans are to hang out with him, you two must be quite close. There's a lot of memories involved. But (The Hermit) you are isolated due to feelings regarding his best friend. You are having to look inside to make a decision whether or not to go. You don't want to miss the birthday, but you need some type of reassurance that if you go, those turbulent feelings about his friend won't bubble up. I can imagine it's a tough decision. But I would look at that third card. It tells me it's time to take a leap of faith. You need to be care free and disregard the nagging thoughts that there's risk involved. Focus on your brother and the nostalgia that brings a smile to your face. I think that far outweighs the risk of a friend with whom you shared a difficult past. He's not blood. This is about your brother.