If you have people on your side of the family willing to go with you, then set a date to get your stuff and let your ex know when that will be. He will have the opportunity to have someone from his family be there, but if he doesn't do that, oh well, too bad. You can still get your things safely and then be done with it. You are very wise to get away from this guy. He has some fairly severe issues and there's no way you can help him with those. Please take care of yourself.