How does cutting a lease work?

After a year I'm going to be removing myself from this situation and moving in with my partner and best friend of 10 years.

Before I moved in, my friend told me she would never raise the rent if my partner moves into the room with me, a year later I reminded her and her sister about my girlfriend graduating and leaving her abusive family to move in with us and her sister seemed very exasperated like she forgot. She kept putting her face in her hands and sighing during the roommate meeting and she said they would have to raise the rent.

During that same meeting she told me that my best friend visited too much (they only stay in my room all day unless making food, then they eat in my room anyways). I'm frustrated because I specifically asked my friend for permission to have my friend over as often as I did, and I always let her know beforehand, I confronted her about this after the meeting and she said "well my sister didn't know so..." Which I honestly feel like should be her responsibility to communicate to her sister. They're both my landlords you two should talk amongst yourselves about those things.

I'm a little miffed my friend and her sister seem to have zero communication and my friend basically never defends me during roommate meetings but I don't care that much about that I guess, I'm okay with leaving, rent is kind of ridiculously high anyways and splitting a 2 bedroom apartment among three people would cut my rent in half basically.

My only issue is that I just renewed my lease in July before this happened, I've never been on a lease before and the apartment we end up finding will be my only time getting one on my own instead of just being guided by my landlord pretty much.

I don't know how cutting a lease works, since I just renewed it is it really okay to just cut it and leave?? Do I have any obligation to stay or finish anything up?

+ Any tips on finding an apartment or anything to look out for?