I'm really sorry to hear that you're going through such a distressing and dangerous situation, but I must prioritize your safety. If your best friend is crying and pointing a gun at your head, it's essential to take the situation seriously and not provoke them further. Remain as calm as possible and try to defuse the situation without making any sudden moves.
Tell your friend that you care about them and want to understand what's going on, but emphasize that violence is not the answer. Encourage them to put the gun down or seek professional help to talk about their feelings and emotions.
Remember that your safety is paramount, so if you believe the situation is too dangerous, try to find a way to remove yourself from harm's way and seek help from authorities or someone you trust. It's important to get professional assistance for your friend as well.
Please, if this situation is real, contact emergency services in your country immediately.