The scene is focused upon the aspect of your mind (represented by the male leader) providing you with a way of thinking that you are to see as guidance and are expected to follow, but here this thinking has the ability to leave you emotionally devastated- very hurt- (male is a killer) and is self destructive. Note aspects of the self (the bodies on the floor) representing ideas you have, that you have the right to use, that are being eliminated. This is something you may have difficulty believing. (Didn't see anyone being killed) The fast food place suggests a situation in which you could buy or accept ideas for emotional gratification which are not well thought out.
The emotionally devastating way of thinking is being shown to apply to your thinking about relationships (you see the killer in terms of a male-female relationship) Using such thinking you threaten yourself with the possibility of being shot or criticized by a partner as an excuse to accept counting upon your own emotionally devastating thinking. Here this is seen as very disagreeable - it "sucks" - because of the emotional self destruction involved. (the human remains & blood) This is not a laughing matter to the True Self.
The bathroom refers to a mental attitude reflecting a need to acknowledge some sin and guilt which in this case seems associated with an animal-like nature. [This often relates to sex simply for sex but without love & marriage.]The impression of a lair - an animal's home - implies such a state of feeling guilty could become a permanent state of mind.
You tell yourself that you are able to use rational thinking (drive a car) but aren't using it here. (don't have a car) A personal attitude that seems good to you (a beautiful bedroom) appears to be one in which sex is plentiful and seemingly endless. With this attitude the True Self would think of using your own mind's ability to think critically (use killer's guns) and be very critical about your thinking regarding relationships (to shoot him in the head) but you do not do this.
The sex scenes indicate that you have a very long standing intimate relationship with a self destructive way of thinking, one in which you have come to actually love this way of thinking. You seem ready to form a permanent bond with this destructive way of thinking. (marry the killer) This is something the True Self chooses not to remember happening. Instead the True Self would see that a higher level of intelligence would be called for to help you stop the wrong thinking. (FBI appear)
As the dream is very long & complex I have abbreviated it somewhat. [An example of emotionally destructive thinking would be a person of normal or above intelligence who persists is thinking they are stupid. By not acknowledging the reality they hurt themself emotionally and can actually destroy those psychological aspects of themself that provide their sense of having intelligence.]