I completely disagree with the post above - what you describe are all classic abuse. The violence, the manipulation, the gaslighting, the degredation (sp?), etc. He's got you feeling so ashamed, so down, that you're too embarassed to seek even professional help. I mean, if you fear that he might use his gun on you, how can anyone say that he's just a big selfish dick? I helped run shelters for abused women in California for three years, and what you describe sets off all the domestic violence alarms.
All I can say is that for your own safety and sanity you need to leave ASAP. And I mean physically leave. I have no idea where you live, and what sort of resources are available, but you do need to seek professional help in getting away. It's unfortunate that people subject to abuse often find leaving a very difficult thing to do, but relationships like this generally tend to NOT get better and often get much worse.
If you are in the US, Canada or Europe, there are often resources pertaining to domestic violence, some of which focuses on the LGBT community. You can anonymously approach any number of resources; your local LGBT center (if there is one) is a good place to start. Even contacting a resource for DV for women (in California, the YWCA often deals with DV issues) might produce some good advice or referrals. Many areas also have DV toll-free hotlines that you can call.
But the most important thing is that you get out of there; nothing is more paramount than your own safety, whatever your partner may try to say.
Good luck.