Music Venue Unilaterally Changing Time A Day Before Advertized Event

Location: Washington, D.C.

I'm kind of panicking right now. I'm a promoter throwing together punk shows. Tomorrow is a show that I booked over a month ago. I've had some serious complications with this place (which I will describe after the central problem). This morning, I woke up to an email from the venue owner stating the following:

"I am writing to let you know that my manager told me in an emergency situation that his friend's Band show was canceled by the venue they booked earlier. So I want to let you know we will push one hour for your show to let this band have an early show from 7-9pm, and you start 9-11. Please make an announcement to your social media and all promotion channels."

I panickedly check the instagram of this bar and they're already promoting this shownew hard at our time slot (8-10). I emailed the venue owner that we didn't agree to this and that we're open to discussing this at 9 am. No response yet, and I followed up through text. I don't know if I'm being impatient, but our show is literally tomorrow evening and they have a band setting up tomorrow at our time.

We have a LOT of logistical concerns riding on our specific time, including coordinating sound. Just this week, the social media manager of this bar said that that bar's brand isn't doing shows anymore and I just have the space and made several disparaging comments at me, making it clear that they're not going to let people know that our show is under their bar through their promotional channels. Now, three days later, it looks like they're advertising under their bar brand again, and it looks like this new band that got moved into the spot is a friend of the social media manager (which I uncovered after some digging). They're promoting this new show on top of mine and I have no way of telling people that see the posters outside that the tickets at the door will be for another band. I'm still kind of stunned. Throughout the entire process of booking, the owner has been very unresponsive and has not been addressing our questions without a lot of prodding.

We have a pretty hefty trail of correspondence establishing that we have this date and time, including a poster signed off by the owner as recently as last Thursday. We've already sold tickets under this bar (they're managing the finances and taking a hefty cut). I communicated that I'm having this issue to the bands, but I really need to know if there's any legal recourse for me (or legal recourse I can mention to the venue owner), and if this constitutes a violation of contract (even if one established by correspondence). I really don't want to let my bands down . These are both young bands that just started playing. It'll be the first show for one, and the second show for the other.