Did Snape Leave the Lake?

The only person that we know for sure apart from Dumbledore and then harry run her my any that ever finds out about the horcruxes is Regular black. Yeah What I want to know about snape in this moment is okay. He had a plan Allegedly he put it in the lake because reasons for all we know he saw the lake and said ah lake Tosses the sword in it freezes it himself then sends out the patronis. So How long after the patronis disappeared? Did he leave though like did he stay and make sure that his plan worked or did he Not want to watch it unfold  I do not see him sticking around for that.