Realm keeps disconnecting all players and resetting to last world save

I tried logging into my realm this morning and was playing by myself for about 5 minutes until I was randomly disconnected. When I logged back in, I found that everything I had done in those 5 minutes had been reset to the state from when I first logged in.

It did this 2 more times before I decided to restart my launcher. The next few logs into the realm, I completed a few tasks before save/quitting and restarting the launcher, to test if the world would re-save. It did work, and I played normally for around 15 minutes, until one of my friends joined the realm.

Within the first minute of them joining, the realm lagged out and disconnected the both of us. When we relogged, all our progress had again been sent back to the original world save. My save/quit strategy had been nulled as my state was that of when I first logged in that morning.

And now the same thing is happening any time someone joins the server, and it is actively worsened the more people try to join. One person can go 5-10 minutes before a random disconnect and a send-back, but if someone else joins during that span, it's then dropped down to a mere 10 seconds before the disconnect. 

We have a sprawling base set up around a village and have breeding methods for them, as well as our normal animals- so we know that it has to be involving their mass population lagging us out. Only one of us at a time is able to log in and try to cull them to reduce the lag, but as soon as someone else joins, all progress is reset and we're back to square one.

Please help us fix this issue ASAP. I've never had this sort of issue before and as the realm owner, I'm extremely upset with having little to no option other than abandoning the save we've all worked so hard on.