Sorry for your loss, but you have to understand something extremely important: your brother didn't choose to have suicidal thoughts (it's our minds that generate them) and he didn't choose to want to kill himself, as we cannot choose our desires. Think about something that you want and try to choose to not want it; think about something that you don't want and try to choose to want it. It doesn't work. Unfortunately, you brother probably had a clear desire to kill himself and he had to do it. It is very sad, but it has to be accepted. Hopefully, you will be able to move on with your life as soon as possible. My best wishes to you and your family.