Cloud,
First let me say not knowing anything about your personal life limits the ability to provide specifics about the dream related to your life. I can only provide an outline of the emotional energies that dominate your life.
My sense of your dream is issues you are not fully consciously aware of issues related to the inner conflicts of your sexuality and your place in the world because of these inner conflicts. There is a constant inner struggle in accepting your sexually and with outer acceptance for who you are and your sexuality among family, friends, peers. This is likely due to resistance from these same people which cause inner conflict. Since these are dominating emotions and a continuous conflict in your waking life it is normal to have such dreams {just as nature gave the body an immune system to heal protect, it gave the psychology} dreams to heal resolve emotional conflicts/issues}.
The dream is telling you there is an inner conflict that you may not be giving enough attention, but also telling you to accept who you really are and be that person and not allow others to perpetuate the conflict {inner and outer}. That message is how the dream ends which suggests it is an on going conscious/unconscious aspect that needs resolution.
Below is my interpretation of the images and actions which provides a final analysis {above}.
-room-hidden unconscious aspect of self-mob-chaos and disorganization, experiencing an inner conflict -nice to me-a superior aspect
-having a conversation-dialog within oneself
-eating pizza-replacing what you are lacking or feeling deprived of
-I was going bring my girlfriend over-how you feel about yourself and relationships
-I went to my van-practicality of who you are and where you are going
-grabbed my girlfriend-clutching onto these type emotions {relationships}
-out from back to talk to them-unconscious feelings {your true emotions}
-slit my neck-a separation between your heart and mind
-stabbed my girlfriend multiple times-constant struggle with emotional energies
-they went into my van and grabbed more people out-affecting your practical life
-some of those people committed suicide-desire to escape aspects from your waking life
-other were stabbed to death-dominating emotions
-mob was shouting over and over-repressed emotions of chaos and disorganization that need conscious expression
-“we don’t deal with no homos”-managing emotions related to a union contradictory aspects
-and then everything stopped and re winded-ending emotional chaos and look toward the future
-just because I told them I had a girlfriend-acceptance of rejected aspects {being who really are}
-I told them I was going to grab my friend from the van-accepting yourself as you are in conscious life
-I brought my girlfriend over without them knowing she was my girlfriend-being consciously aware of inner unconscious conflict
conflict
