New partner is an ex sex offender

[Greys26]

Hi there im looking for some advice. Iv seen a gew post from similar situations that im in but i wasnt sure if the same would apply to me. 

Please no judgments on why im still with him etc. 

Basics. I have a 6 year old son with my ex partner. And i am now in a relationship with my new partner since december. Hes was around my son from may until middle of june. 
Iv then found out about my ex partners past. So all contact has been cut as social work etc are involved. 
My partner was convicted of a sexual assault on a minor when he was 15. It was is younger brother (he was mentally and physically abused by his step dad, brothers dad so snapped and hurt his brother to get back) he was never jailed and did all his meetings parole visits etc as required. Contact with his brother remained in place only it was supervised with other family present. He was deemed little to no risk and served 3yrs on the SOR.

My ex partner isnt happy for my son to be around my partner which i understand. However he been told he can keep my son full time if he feels hes in danger. 
I have stated that my partner will never be around my son if thts the case. Hes also stated social work have told him that while my partners assessments etc are on going if i continue to see him social work may decide to place my son with him. Is this true? 
Can i have both? Like live with my son and only see my partner when hes at school or with his dad etc? 

Social worker has also stated they do class me as a protective factor as i have cut contact etc since finding out.

I really just need advice on how things will proceed and if im likely to loose my son because of this. Can i still maintain a relationship with my partner? Can we have a future, kids, marriage etc.

Thanks