so i was looking at 斉 today and now im crying lol

ugh so i spilled my iced coffee all over my desk today while trying to write down some vocab for my class and i got so distracted but anyway i was looking at 斉 and i swear my brain just completely melted because it looks so much like 済 or 斎 or something?? is it read as sei or sai or what, i keep mixing them up and now i don't even know what 斉 is supposed to mean here lol help