Pull it back up, then take some masking tape and stick it on there tight enough where the branch will stand like its still attached
Then add a stake for extra support, and check it in 3-7 days you'll usually be fine... 99% of the time in veg you could reattach that with barely any slowdown. Flower is a bit tougher as the stems harden and Im really not positive that regenerative/reattachment trait is as effective in flower. Either way, No big deal in the future (You probably already cut it off by now..)
In fact, when reattaching branches like this in veg, they can sometimes be stronger because they grow a sort of "knot" or calcified spot on the stem like if you broke your arm in one spot, it would heal and grow back stronger than before... Same idea sort of.