I suppose you could mention it in your will, if you plan on leaving one. It's not uncommon for wills to be read before the funeral service, but make sure you instruct that your will is read before your funeral in your suicide note, if you don't feel comfortable discussing funeral arrangements in your suicide note, since any family member including the ones you don't want to attend your funeral can read your note, but only an executor can read your will. Your will could have your funeral instructions such as place of burial and directions in regards to your memorial service including anyone you don't want to attend. An executor (personal representative) would be in charge of your funeral arrangements and would have to follow your last wishes.