Welcome back to our Forum. I know that you are battling OCD and worry about such things but there is no reason to worry about this event.
While your experience was not very hygienic, there is no meaningful risk of getting any STD, bacterial or otherwise from this exposure. The microbes which cause STDs tend to be very fragile and die quickly upon exposure to the environment. Further, there is a biological tendency for organisms to "stick" to the fibers present in paper or clothing. There has never been a case of STD transmitted though contact with previously used toilet paper or material and I am confident that you will not be the first. No need for sorry or for testing.
I hope this comment is helpful to you. EWH