Made a bad choice
I have suffered with depression and anxiety for a long time. It has affected me very badly and caused me not to be able to think logically about things. At the moment I am having a bad time in work and I feel like everyone hates me there and I don't belong there.
These feelings have made me all confused and I feel I am making a lot of bad decisions. When a work colleague asked me to join her and another work colleague for some food in her garden as a way to hang out after work. I said yes because it made me feel wanted. I went and I now feel so guilty because we are in quarantine. It was so selfish of me.
There is no excuse for what I did but now I can't stop thinking about it. I feel ashamed, guilty and anxious about the whole scenario. I feel I could lose my job because of it. I don't know what to do.
I'd say that you are too worried about the visit. People are social creatures, we crave interaction and need it for good mental health.
I don't understand some of your explanation, the part where you said you are now in quarantine...did you actually give someone covid? If you didn't, then I am confused as to why you would feel selfish and ashamed.
I'm confused, too. As noted, if all you did was spent time with people in a garden, that's...not so bad. I mean, it might be breaking quarantine, but literally *everyone* is doing that. (Including, obviously, your colleague who asked you to join her and another.)
If you gave someone COVID, that is unfortunate. But that was also a risk your colleagues took when they invited you/accepted the invite. It's as much on them as it is on you.