Regarding evidence obtained by phone recordings in my house

Hello. To find out that my wife cheats on me I left an old phone in a closet in the living room to see what’s happening in my absence. I got a lot of evidence and found more about my wife mistreating our baby daughter by shouting and threatening her to beat her a lot. Found out that she and her mother were talking very bad about me all the time in the presence of my baby daughter, and they were having a constant campaign of defamation on me to everybody that knew me and who they were talking to. Sometimes I was recording our conversations as well. They were not aware of this recordings. This recordings have a lot of evidence that they were not emotionally abusing me, defamation, cheating and child mistreatment!nWent to the police and they said it is illegal to use this recordings even if they are for the social services only. nMy question is: are this recordings illegal in uk? And can I use them? And if I mention about them to the system how will impact me? What will be the damage?