FIL is bringing special snacks & food to his grandchildren but not my son.

The past 3 weeks my FIL has been coming over to take care of my kids while I work since my husband passed away. I have 4 kids, 3 with my husband and my son from a previous relationship. Right now I'm struggling to keep afloat in this economy as I’m sure many of us are. Waiting on SS benefits & life insurance but my bills are paid, there is food in the kitchen… no junk food or treats but food nonetheless. I only eat every few days to ration but I did notice our lunch supplies lasting longer than usual.

My FIL never warmed up to my son. He isn’t mean to him, he just doesn’t go out of his way like he does the other 3. Tonight he came to me asking if he could do some chores to get money for snacks & yummy food. I told him things are really hard right now so I don’t have “chore” money but hopefully soon I could.

He then asks how his siblings got snack money if I didn’t have money to give him. I said they don’t? I asked my kids what he meant and apparently their grandpa has been bringing them special treats and food when I’m at work but telling my son they give him money for it. So that's why my son gets nothing.

My FIL also has been ordering food for lunch but making my son eat what I have in the kitchen. My grief has made me a total zombie that I didn’t know this was going on.

I confronted my FIL and he got defensive. He told me I couldn’t tell him to not spoil his grandchildren, his “flesh and blood”. That his grandchildren lost their father and by spoiling them, he is helping them grieve. Completely discrediting my son’s loss like he didn’t lose a dad himself. My husband loved and treated him like his own.

Yes, my son isn’t my FIL’s blood grandchild but it’s incredibly cruel. I need my FIL to be here but it’s upsetting my son. My FIL said he would continue to do as he pleases and to not tell him what he can or can’t do.

I’m furious but I don’t know what to do.

Throwaway for privacy & I did have this on another sub but I think it's more appropriate here because I want to vent not judgment.