TMI Pic: Did his affair lead to an sti?

Sorry about the really gross picture ...I have been having this discharge for about a month now. I went to the doc this morning and my period is two days late but the doctor said that the test is negative for pregnancy. I get the results for the STI test in about a week and a half since the holidays are kind of in the way. My husband was having an affair and didn't use protection. The discharge started around the time the affair began. It has the slightest hint of yellow and the smell is real hard to describe but it is unpleasant. Everytime i go to the toilet, i can feel it come out. And its sort of a lot... by the way it did take me a while to get tested because I didn't find out about the affair right away. And I'm a teacher so it's super hard to get a day off