I've been in almost the same situation, but it was 6 kids, and no aunt. Also the SOB didn't turn the gun on himself. I know how it feels. Especially if you are very close with them. I know the thoughts that run through the head. If you ever wanna talk, pm me and I will give you my home number.
I know it's hard as hell but stay strong, I wish I could say you can get over it, but truth be told, you can't. You can go to not thinking about it all the time, but it still hurts the same when you do.
My prayers are for you tonight brother.
Rev. Michael