To cut a long story short, FIL is pretty toxic. He has a long and varied history of seriously unreasonable behaviour and selfishness. He regularly tells DH how he is a terrible son and how flawed he is as a person. DH is neither. FIL is never wrong and blames all the ills in his life on other people. DH tolerates him due to FOG.
DH tries to minimise contact with him as it's difficult and often painful, see above, and usually just gives FIL additional fuel to flame DH with. FIL lives quite a way away so we don't see him that often.
Recently, out of the blue with no previous discussion on the matter, he wrote to DH stating that he will no longer be giving the DC presents at birthdays and Christmas as they don't contact him, for which he holds DH responsible. They are 12, 9 and 7 years old. All 3 birthdays have since passed and he didn't acknowledge any of them in any way - apart from when our eldest DS answered the phone on his birthday and FIL asked him why no contact [confused face from DS]. He didn't wish him happy birthday.
DH has told FIL that he has crossed a line, that if FIL continues to make DC feel bad/guilty then there will be no contact with them. FIL says he will continue with the no presents/acknowledgement thing until they contact him enough [god knows how much/ by what means/ how often would be acceptable]. I strongly feel this is the start of his toxicity leaking into the next generation and that this can't be allowed. Does anyone have any experience to share or advice to give? My blood boils.