Anyone know the best approach to creating a simple WYSIWYG editor for a custom file

It basically uses
~B - Bold
~F - Fixed Width Font
~1-9 - Colors

IE: ~B~1Bold Green~B ~2Regular Yellow ~FFixed Width Yellow ~3~FRegular Red

Now I originally though of just parsing a RTF file and exporting the plain textfile which works but is hella slow... anyone have a better method?