Affidavit writing is an art form. This isn't complete, but it should be enough to get you started:
Only include what is relevant. An affidavit can certainly be 6,000 words long, but I'm betting there's a lot of things that can be chopped out.
Set it out clearly in numbered paragraphs. Unless it's very basic, introductory things, keep it to one idea per paragraph.
Stick to the facts: who, what, where, when. Unless it directly relates to you, forget why.
If you didn't directly witness it, you can't include it.
Only put down things you directly witnessed, and be clear about the circumstances. For example, don't put "X told Y that Z happened". Instead, you should use something like "X told me he told Y that Z happened", or "I was present and heard X tell Y that Z happened."
You can't comment on anyone else's state of mind, so don't. You can only put in what you say them do, or heard them say.
You can comment on your state of mind, but be careful about doing so. Only put it in if it is directly relevant to what happened, and give a reason why you had that state of mind.
Try and keep it in order. Chronological is probably best. By topic if relevant.
Don't draw conclusions. That's not the job of an affidavit: it's your evidence. The court draws conclusions.
Unless you're an expert on something, and have the credentials to prove it, don't give your opinion on something unless it's extremely basic. For example, don't say: "X fell down and broke his arm." Say, "X fell down and hurt his right forearm." Even a doctor witnessing the event would need to break it down, eg: "X fell down and hurt his right forearm. I inspected X's forearm immediately after the fall and considered he might have a broken bone. On Y, X had a X-ray of his right arm taken at Z hospital. The results of the X-ray showed that X had a fracture of his right ulna."