This really sucks man!
Here is what I woud do.
Finish your grow, get everything out and have a talk with him. See if it's possible to work things out on better terms for the both of you, ideally without you having to cuff him 6 months rent, unless that is a rquirement of your lease.
If he does not ant to talk, pay him according to the exact lease terms, by check payable to the order of the landlord. If lease says you have to pay rent until he finds another tenant, then give him a few pre-dated checks to cover each months's rent individually. As soon as he rents the place out, contact your bank and cancel the uncashed checks.
As long as your plants and equipment are out before you go talk to him, you will be ok. If for whatever reason things get ugly with him and he threatens to show the pics to the cops, well, like lots of people said, he broke the law to take the pictures so...
Good luck man, hope you get your life back on track soon.
BC