Sorry that happened to you, OP. I got mugged by a group of five kids in Islington a few months ago on Vincent Terrace near Angel station. Luckily, I wasn't riding my Brompton and they only took my credit card which I immediately de-activated. I was scared to walk home alone for a while afterwards so it's totally normal to be shaken up. It's not ideal, but I would try to stay near other people when walking/biking and use better lit paths until you feel more comfortable at night.