Degrading yourself is not going to help since you will probably just bring yourself down even more.
So you had an extramarital affair - its over and you have to live with that.
Feeling sorry about it won't change the premise that you had one.
After 7 months, I doubt that your tingling sensation at the penis tip could be related to an STD.
Red spots can be an indication of Herpes, but since the timing is close to masturbation, a good chance is that its not STD related.
If you are worried about a potential STD, then go get tested and find out if there's anything to be concerned about.
In the end, if one of your tests comes back positive (though the likelihood of that is relatively low), you have to protect yourself and your wife.
I messed up and had an extramarital experience about 7 months ago. I am scum and I am shamefully guilty. Just recently, I am experiencing some tingling in the penis tip, almost a burn but not quite. No burning during urination, no other symptoms. I was thinking trich or chlam. Is that possible? My wife shows no symptoms nor does the other woman. It has not happened again and will not happen again. I am sorry for what I did.
Your red spots can be many different things and probably not STD related since the timing of it is after masterbation. Oral sex is low risk to aquire a STD, but it is possible, but without any symptoms I doubt that you have anything.