Hello!So sorry to hear about your problems on roaches and bed bugs. When it comes to bugs and pests infestations the one responsible to pay for it is the landlord that is unless proven otherwise that the tenant brought the pests and bugs in. In your case since the infestations occur way before you moved in then your landlord should pay for the treatment to get rid of it and since he is playing stupid and do not want to fix your problem then the nest logical step you should do is to file a complaint against your landlord. You can file your complaint with the RPA through this link http://www.rentalprotectionagency.com/complaint_center.php?id=51dd308610038

Breaking a lease is really hard to do and almost impossible without some type of legal help.  I did it though, and I’m sure you can too.  The rental problems you list are annoying but probably not enough to get you out of your lease.  Try filing a complaint, here with the RPA.  It says they can help you with noise violations and early lease terminations.

I saw you were located in Utah.  I also rent an apartment in Utah and have had similar problems with loud neighbors.  Do you know what I did?  I became friends with my loud neighbors.  Its amazing how far a plate of cookies will go.  If you really want someone to change their behavior, get them to respect you.
 
It will be a lot easier for your neighbor to be loud and selfish if he can’t stand you, VS if you get to know him and eventually show him how easily noise travels into your apartment.  That, will solve your problem.  Of course its easier to file a complaint; but this option will be more effective.

To terminate a lease its best to have proof that your landlord breached their lease agreement.  I think you may have a case if you can come up with a way to prove that your apartment neighbor is using illegal drugs and then complaint about it.  If nothing is done, send your manager a certified letter stating that they are in breach of your agreement as they are not taking appropriate action to stop illegal activity.
 
In my mind, that would be the best shot at getting out of your lease.  Noise problems can also be effective if you can create a paper trail of police reports showing a problem, then again, complaint to your property manager.  If the noisy neighbor continues, send a certified letter stating that they are in breach of agreement as they are not appropriately resolving noise violations that are resulting in a breach of your quiet enjoyment.