My father has been threatening to take his gun, shoot up a Walmart, and kill himself. I think he may actually do it

I (17m) just found my dad's (51m) gun collection in his basement. It was a disgusting sight to behold. Rack of deer antlers in the corner, taxidermy hanging on the walls, hunting gear everywhere, and guns. So many fucking guns. I estimate he had at least thirty guns spread out across the room in various cases and on a gun rack on the wall. I recognized a model from one of the hand guns and looked it up, and it's the same make and model of handgun one of the shooters in El Paso used. <br><br>I don't even know when my dad bought these. He doesn't go hunting. At least not lately. He's a good hunter, but I think he has stopped because he hasn't been able to get out of the house anymore. My dad has been a shell of an man the last year and a half since my mom died. He has gone from a vibrant, intelligent, and loving husband and father to a bitter and depressed man who stays in his room all day. He doesn't want to see the family, he doesn't want to be social, and he spends all of his time in his room. It's gotten to the point where we have to call and check on him because we don't see him at all.<br><br>I'm afraid of what might happen if we don't do something to stop it. It's not like we can call the police or anything. My dad would take it as an attack on him if we did that. He has already been spiraling. He has gotten more and more bitter the last month, and he has started making threats. I can't remember all of them, but he has mentioned shooting up a Walmart and killing himself. He mentioned it in the same tone as if he was joking, but he has brought it up multiple times. He has also mentioned killing the family and then himself. He has said he hopes we will "make it easy for him" and not stand in the way of his "decision."<br><br>We have tried to get him to get help. I don't know how much money he has left. We tried to get him to go to therapy, but he refused. He wouldn't even go to a dinner with the family, and that was weeks ago. We invited him to a dinner to help him get back and be part of the family, and he refused. He has refused every attempt we have made to get him to join us.<br><br>I don't know what to do, and I don't know if it's even my place to step in. I'm not sure if I'm overreacting or not. I just don't know what to do, and I need help and advice. I want to call my aunt or uncle to tell them about this, but I don't know if they will just get angry at my dad for his behavior. I don't know what to do, and I don't know how to help my dad.