I gave up

Haven't seen my children now for over 4 years, I gave them up due to my mental health issues ( depression and anxiety) I knew it was getting worse and I knew my children would be better off living with their dad. Since then I've been accused of sexual abuse, physical abuse, taking drugs, I was having video calls 3 times a week and apparently my children was terrified of me, I was having monthly visits and apparently the children had nightmares about me, I've been accused of the worst things possible and been interviewed by the police several times and no further action. My mental health is better and would like to start to get a bond with my children as I miss them, but the dad and step mother has made sure I can't... Please help