I'm pleased you chose the name you did, it fits in well and there is indeed a lot of hope. I've had an anxiety condition for a pretty long time and can understand exactly what you are saying. Whatever you do or think the thoughts follow in and you are left questioning what you did, and feeling pretty horrible. A real trap.
The people that say "let it go" simply don't understand that it is not an option. You get that a lot, if they have not been there they can't really advise.
I don't think you try to treat the guilt, which is a sort of byproduct. You treat the basic cause. I am miles better than I used to be and that is because of three things. Medial treatment, personal support and trying to combat things myself.
So if I was in your position I'd go see my GP and in a long consultation explain what is happening to you and how you feel. Write it down first if you think it might be hard to explain -I did, than shared the paper. Hopefully you will be diagnosed and started on a path to better things.
I found my family's support and the fact I did not have to hide my feelings and what was going on was a great help. Do you have anyone, partner, family or friend you can talk to, who will care and want to help?
Apart from that I try to deal with these thoughts as they come up, by exercise, moving away from the scene, distraction so my mind goes into another space - I use books and movies - plus if things get too bad I use the free smartphone app Smiling Mind to occupy my mind - good but takes practice.
I'd suggest you have a look both at the Anxiety sections of The Facts menu above for background information and around this Forum to see how some others have coped.
If you would like to come back and talk more that would be great