CO PARENTING WITH A 21 yr old

I’ve been gone away from this app for a good two years now and ever since..i finally decided to leave my baby father because it was the most toxic relationship and bad for my son i did not want him to grow in that environment. Currently I’m having trouble co parenting with him because he holds a grudge on me for “breaking” our family apart ..soo he’s been making my life extra difficult . I even had to take him to court for joint custody cus j don’t want to take away our child from him .