You are overreacting. No risk situation. HIV can be only spread through unprotected vaginal / anal intercourse or sharing needles with other users to inject drugs.
No, no possibility to your proposed scenario of hiv sperm residue on her breast causing HIV. Air inactivates the virus as does saliva. As mike_no states, the only way to get HIV is to have unprotected vaginal or anal sex or share IV drug needles. So, you were safe and had zero risk.