Crashing when trying to join server in multiplayer server. Not actually version 1.13 I am using version 1.12.2.

Hi was wondering if you could help me today. My Minecraft is having an issue where if I go into a server specifically "play.popularmmosworld.com" it will load in and let me move around but if I attempt to join a server within the world the stops responding and I have to hit the red "x" in the top right of the screen and hit the button "close program". I have been trying this for about almost a week and nothing has changed. Also if I try to join a regular world that I had made it get stuck at the "Loading World" screen and that's it I cant exit out of it so if you could possibly help me that would be greatly appreciated thank you.