@oviraptor21
What

So OP isn't allowed to have a night off ever?
What about when DS is with his Dad, or if OP is out and has got a babysitter?
Sounds like DS looks forward to the BF being there and it's a treat for him to be read too by BF. What a shame it would be to spoil that.
OP has clearly known this man for at least a couple of years. At some point she must have decided she trusts him. Does she have to keep him at arms length for ever?
Most paedophiles are very manipulative, and this means kids can have a strong attachment to them as it completely messes up their understanding of the world and nornal relationships.
(eg young teens thinking the grooming Rochdale rapists were their 'boyfriends').
So children can really 'miss' their abusive (step) parents/family members when it is disclosed- kids will have attachments to people including those who abuse them, emotionally, physically and sexually.
A small child may trauma bond to abusers, also many kids who are sexually abused are terrified of what their abuser tells them :
A few examples from my experience:
A four year old whose experience tells them that sexual contact is normal with adult males is normal, so will ask Uncle X to bathe her as he sings funny songs and tickles her...
'It's our special secret' ... I recall one five year old distraught as he had 'broken his promise' and told his teacher about his sore bottom (uncle-attempted rape)
If you tell anyone, you won't see me again, and mummy won't have any money and you'll all starve- you dont want your baby sisters starving do you? (father eventually convicted for raping his daughter when she became pregnant at 12-he'd been abusing her from infant school).
Please don't be hopelessly naive.
It is truly, stomach churningly, awful to be with women, when they suddenly realise that their wouldn't-hurt-a-fly /he's - my-rock boyfriend has been grooming and (attempting) rape on their most precious children.
Please dobt be part of that group