I do not think you really injured yourself: you just overdid it a little for the first time…
In two or three days you should be like new.
For future sessions, warm up before, with a little jelqing and a little heat and then slide in to the tube and apply pressure slowly and progressively.
You must feel comfortable, no matter if the gauge tells you could pull another HG, if it is not comfortable it is no good.
Begin with one short session a day at very low pressure and do not try to pull your unit to an extra inch of length in few seconds, feel the flow of blood which slowly fills your dick.
After a week or two you can start doing a morning and a night session in the same light manner and after a while you’ll start to know your limits and do what you want.