Why won't my brother and sister give me space after i lost my fiancee......?

My fiancee was 8 months pregnant well she was on her way home from her parents and she would of still been alive if i hadn't asked her to come home before it got too late. Well she was three blocks away from our apartment and got hit by a drunk doing a 100mph that went through a red light and she and the baby both were killed. Well that was 3 weeks ago and to be honest i have been super depressed and honestly been contemplating just offing myself i didn't just lose my fiancee i lost my son as well. Well my big sister and brother have been staying with me because there scared there going to lose me as well and i suppose that's true i guess but they won't give me any space took both my handguns knifes sharp objects meds and every bit of alcohol and took it to my parents. I don't understand why there treating me like this! How can i get them to back off? Advice? Would it be wrong to make them leave my house?