I'll review the document on that point, but then practically what would be my options here? If I just don't give him the July rent that I disagree with he just keeps the deposit. He definitely knows what happened, as to whether it was intentional or not I may never know, but I tend to think it was. What is the mechanism for me to try to argue this? I'm thinking of contacting the real estate office that drafted the original in error, but don't really know what they can offer other than "oh I guess we fucked up on that first contract"
I think your options, in order of preference, are:
1. Find another tenant for them and hope they're cool with that.
2. Find someone who wants to sublet for the month left on your lease (probably tough to find in Charlottesville, and also your lease may have a prohibition on subletting). Or AirBNB it, or something like that to get some of the rent money back (this would obviously require leaving it furnished to some extent).
3. Realize you are partially responsible for this situation. Pay the extra month's rent and treat it as a teachable moment.
4. Don't pay the last month's rent. If he keeps the security deposit, then you can sue him for its return, which will require the court to interpret the lease to see if he was justified in keeping it. I think this is your only chance of getting a legal remedy, but it will probably not be worth the effort (I don't know how much the rent is) and there is still a decent chance you will lose.
I wouldn't just not pay the June rent, because if it ends up in court, the court could see it as you breaching before he did, which could kill any claim that you have. He won't be potentially breaching until he unjustifiably keeps the security deposit, so unless he tells you that he's going to do that, which
might give you an anticipatory breach justification for withholding rent, if you stop paying rent before he gives you an indication that he will keep the deposit, then you are the one who breached.
Also having two months' rent in play makes it a lot more likely that he will take you to court or send it to collections or something like that.
Keep in mind that none of my advice is coming from someone with a law degree, and therefore you shouldn't treat it as such (although it is coming from someone who booked his Contracts class).