There is your answer Ida as Rock Rose said set up a camera and catch it all as it happens ,then you can show the father,what is happening ..
I doubt therapy would do much good since the boys are on their own so much of the time. If you have good relations with the father I would discuss it with him. I should think that the best of all possible solutions, given the situation, would be to separate the boys for a while. That might means having the younger boy live with his father, at least temporarily. Are there any objections to that solution?
They need more supervision and you need to protect the younger child , it is abuse and bullying..so seperate them, have repercussions for the bullying, No TV no Videos no Computer, The 13 year old maybe needs some counseling ..you have to be tough with him and stop his behavior the other child needs protecting ...its in your hands ..
If the 12-year-old is threatening suicide, I would believe the 13-year-old is hitting him, and would let him live with his dad rather than insisting he stay to be tortured every day. Is there no way to get them into after-school care so they are a) separated and b) supervised? They seem very young to be left to their own devices all day long.
Honestly no 1 knows. Like u said your at work and only the boys know the truth and 1 MUST be lying. Maybe u can set up some hidden cameras and see what's really going on. Another thing u can do is get a babysitter. I mean I know they r a little old for that but its a good way to make sure your boys r safe and that there really isn't any kind of bullying going on in your house. I really hope u can find the answers u need. Don't give up and stay strong
Get a couple video cameras and set them up, and watch for yourself. What a shock that would be to the older one.