AITAH for receiving child support while children are grown

AITAH for receiving CS while kids are grown? I have (4) children with my ex and never received CS while they were young, ever. They are now between 23-31. One daughter (very recently widowed) lives with me with her (2) small children since the passing of her husband and the father of her children. I just started receiving CS arrearages maybe the past 5 months and baby father is on me to drop it. Also, I am owed $85,000.00+. I feel guilt tripped and I am not sure if I am truly wrong. Also, I do cover all living costs for my daughter and her children while she is still healing and getting herself together because her husband was the breadwinner.