Shalom in Yeshua Kellie_69,
Thank you for sharing with us your feelings. When I lost my first son (7 months old) I too was devastated, but I was fortunate to have a strong faith in God, and I asked Him why did He take my boy? Several months later as I was falling asleep after working nights, as my wife left the bedroom I saw him following her. He had grown and was toddling!! I realised that he hadn't gone, it was just I couldn't see him. So I can relate to you feeling you son around you. Talk to him.
You should all talk about what happened to PJ, together as a family. You should try and get your oldest son to talk about his brother and remember the fun things you did as a family, as they grew up together.
Finally with regard to the boy who took your son. Whilst you still have a lot of anger towards him, you have already started the slow process of forgiving him. You may not realise it but you have, otherwise you would be still be full of hate. This is good for you because carrying hate is not good for you.
I will pray for your and your family
God bless you