Reasons why Hollandaise sauce will break:
1. The butter is too Hot. Hotter than Hot tap water will be difficult to control.
2. You have added to much butter. If the sauce is thicker than store bought mayonaise you are on the verge of adding to much butter. Add a little water then continue.
3. The eggs are old. Discard sauce and eggs. Start over with fresh ingredients.
Don't rush if you are using butter that is on the upper end of almost hot.
Sauce can also be made in the blender or with a hand blender. Processor is not recomended for small batch such as this.