Minecraft teleporting on LAN server gone wrong

I started a LAN world with my sister and everything worked fine for some time. Just now the 22. December 2020 I wanted to teleport to her because she found a place which was probably far away. And when I teleported to her everything stopped loading and the game kicked me out. I tried rejoining but it didn’t work. The chunk isnt loading and if it does I have just some time to move around but everything else is frozen and I cant use anything. After that small time is over I get kicked… Before I teleported I had a cat and I was next to a bed. I used the bed as a respawn point just incase the cat doesnt teleport with me and then I teleported to her. I used many commands such as forceload and /kill Exilium31 (me). I hoped that I could respawn back at the bed but it wouldnt even let me respawn… Help me

I wanted to add that I allocated all the ram which was available. I also am not running the server/world. It’s on my sisters mac but she uses Windows on her mac. Maybe she needs to change a little bit on her computer.