Rights over children spending time with a violent ex prisoner

[Helpwilson]

First time on here recommended by a family member and hoping I can get at least some information if not a definitive answer.
I am a father of 3 to my first wife (ex) separated for 2
years. I have recently found out she has moved in her new boyfriend that has a previous charge for wounding with internet when he stabbed his ex girlfriends partner in a violent unprovoked attack whilst drunk and on cocaine. Obviously I have concerns that he is around my children even though they have said they ‘like’ him and get on with him. My youngest is a daughter who is 5’years old next month. Have a got any rights to stop him being in their lives or can I get a court order that he can’t be with them without someone being there for my peace of mind either a professional or a third party person who can relay to me what happens and try to settle me thinking the worse.
Thanks in advance and I hope someone can help.

[EnglandPi]

You should voice your concerns to social services.

[Bella640]

You can apply for a prohibited steps order stopping her BF from living there, if social services are involved, then they might support you.