As you obviously understand, your gut/emotional concerns are unwarranted and your intellectual understanding is correct:  no risk. From the earliest days of the AIDS epidemic in the mid 1980s, before HIV was discovered or known to be the cause, health officials accurately told the public that it could not be transmitted by non-sexual, non-blood contact. How did they know? Because there simply were no people with AIDS who had not had unsafe sex or shared blood with other people. For example, no cases at all in people who shared households -- including bathrooms, kitchens, towels, etc -- witih AIDS patients. That earliest experience and knowledge are exactly the sorts of contact you are worried about. The biological reasons are complex and I won't go into them here, but the sorts of contact you experienced simply cannot transmit the virus. It's the same for all other STDs as well. (They call them "sexually transmitted" for good reason:  the causative bacteria and viruses evolved so that their transmission requires the intimate contact of sex.)

So no worries at all. Zero chance of HIV and all other STDs.

I hope this has helped ease your concerns. Best wishes--   HHH, MD

Is it theoretically possible that an infection could be transmitted by a used towel? Maybe. But it has never been known to happen. Contact with a towel does not expose those tissues and cells that must have contact with STD viruses and bacteria for infection to take hold. I agree with what you have been told by your friends or others. For sure there is no need for you to be tested.