I'm sorry to hear about your problem. Since you said you've been natural for a few years, I'm assuming you used to straighten your hair. This may mean that your hair is probably damaged. You may need to do protein repair treatments if this is the case. just to repair the areas of your hair where the breakage is ocurring since these areas are weak. It also sounds like you need some intensive moisture treatments. Are you following the CG method? If you are not then your problem probably won't get better until you do. If you are CG then i would do a protein treatment 1x a week followed by a deep (1 hour+) moisture treatment.
Also, I wouldn't braid or twist your hair. Even if it is gently done it is still putting stress on the areas that are weakest in your hair. Sally's sells the silk/satin head wraps (in the black hair section). I would wrap it securely around your hair, then you can put the bonnet over it. This will help keep your hair from moving about while you sleep but also protect it from tangling.
As far as split ends. This is an indicator of a severe lack of moisture. Regular trims will help but you also do a little home treatment. Put a mix of honey and EVOO on the dry ends before you co-wash. Let it soak in for 10 minutes, then co-wash and condition. This will help keep the ends sleek and hopefully help condition them and prevent split ends.
3a/b, very dry, fine/med-coarse, high porosity
CG since 7/27/09
Bella Curl Products
CW: protein free-cleansing creme
CO: protein free MRcondish
Styler: FSG + protein free LI Elixir, Gellie, Shine & Seal Serum
Lady of Elixir, Keeper of the Secret Blend, in the Order of the Curly Crusaders