When riding your bike and you desire to come to a halt, please ensure that you use the brakes, located at the ends of the handlebars, rather than your elbow, which is located in the middle of your arm. YOU HAVE BEEN WARNED!
You just found the proper retro way of bringing your bike to a stop, that's all
Looks like a decent injury! Perhaps we should have a "Retro wounds" thread for members to show off their retro riding related gashes (and Taches as I see from your photo ).
Went out for a spin today and my formula r1/rx hydraulic brakes stopped me and my bike lovely jubbly. No neef for elbows, knees or any other part to get involved. I recommend you try some.
That looks pretty sore, a squirt of aftershave will keep it clean but willl sting like Fk.