Should I let DC son go?!

[Mummaonherown]

So my ex is in a new relationship, 6 months, after 5 months he moved in with her she has 3 DD (all under 10, youngest 2.5) he's lied alot about the situation, doesn't pay for our son (I have a CMS claim ongoing but he's fraudulently claiming UC while working) earns very well as a bricklayer in London. He has seen our son 2 times in the last 7 weeks, no over night stays, refuses to do medation. We hadnt seen each other for 5 weeks, he came to visit our son on Easter Monday, within 30 mins he was taking his clothes off "trying to have sex with me" and saying "if you don't do this, we will never get back together" he said alot more and again on Sunday he came to visit and tried it again, admitting the relationship wouldn't be for "a long time" and he would "leave" if I said I'd get back together with him.
He has now asked me if he can take our DC out for the day for his GF and her DD, my son has met them before (back in February) but I feel very uncomfortable with my DS spending time with them, as I know my ex will break away at somepoint and he will cheat on her, with me or anyone that gives him a chance.

AIBU for stopping my DS from spending time with her and DD when I know what my ex is like? I feel so sorry for her youngest who has already started to call my ex daddy (I don't think the dad is around)

Like me, you must be wanting to exchange the ex for a better specimen. One that puts your child first.
My answer on should you help with meeting the gf and kids would be; no. No way.
But do collect evidence of what he said and tried to do to you. If you only respond without recording the reason, you might come across as bitter and not the good mum that you are; protecting your child from heartache.
From experience I can tell you that no one believes a mother when she only tells about the shit the ex and father to dc put her through. Everyone will think there are two sides to every story and it takes two to tango etc. So record record record. You might need it in the future when the ex decides to take you to court, ofcourse not because he wants to care for your son but to make your life difficult.

Recording does not only mean pictures or audio, if those options are not there, it can also be a journal with dates time and timeline of events, your thoughts on it and the explanation of your decision.
Complemented with actual evidence.
Good luck!🍀

No! I agree, try to record if you can. I had a childhood friend who moved in with his new GF and her 2 children, it lasted 8 months when the honeymoon period faded, sounds like he's trying to keep you there as he knows the relationship won't last.

Shambles of a relationship, and I would let my DC be part of it.
X

Your relationship with your ex or not
Is separate to your ds right to see his father if it is safe

If it is safe in terms of his care for your ds then facilitate contact
Yes fine pick him up at 12 pm on Saturdays.

Your ex trying to have sex with you is separate and up to you to put the boundary in place eg . No you cannot come in the house. You can pick up ds at 2 pm on door step .

If you trust ex to take care of ds then he should have contact

If ds would not be safe in his care you build evidence and let him go to court.

What would judge say? Having a new gf does not equate to unsafe in all cases
If you get a new dp does that make you unsafe?

the CMS and trying it on with you are irrelevant when it comes to his relationship with his son.

as hard as it is for you unless there are safety concerns which it doesn’t sound like there are then you can’t stop him having a relationship with his father.

I agree. Two seperate issues; contact with the father of your son, and facilitating contact with ex's new gf and her dc.
The latter I would prevent as your ex is asking you to help him with this, you are able to say no.
Hopefully he still has interest in his son when showcasing him with the new girlfriend is off the table.
But make sure you document it all.

FGS report him to inland revenue and benefits. Everyone else has given you good advice on handling contact.

@cestlavielife he doesn't bother with my son no more, unless he has a day out planned with his gf and her children. He didn't bother to see his son for 5.5 weeks, I was the one chasing him for days/asking him to call his son, he never did. He then asked if he could have our son stay the night at her house, I said no but he can see him weekly.

He saw him on Easter Monday, then again on Sunday, but because I told him no more in my home and I wasn't going to lend him money - he's gone funny on me. Called me a 'scrounger' yesterday when I asked for some money and then this morning said he will only see our son on Sunday if he can take him for a day out with his GF.
He will never ever go to court, he's refused medation 3 times, the reason why "because I don't want to do it"

He has only known this woman since November, I'm extremely uncomfortable letting my son be part of this set up, when my ex is already making plans to leave her, either if I say yes, let's get back together or he finds a better offer.

He introduced his previous gf (April - July) last year to him, within a month.

@Sirzy I haven't stopped it. He was the one who decided to go 5.5 weeks without seeing him or calling him, it was me who was chasing him. I was told to stop, so I did.
He doesn't want to do medation, refuses to do it. He doesn't do anything, he was supposed to pick him up from nursery today, he completely forgot and said "I've got plans now"

@RandomMess it's been reported, I done so in January this year. Can take anything upto 6 months

You might decide to get a CAO in place at some point but in the meantime stop chasing him. If he wants to see DS then let him make contact and you need to have boundaries and he picks him up at the door. Then when he does see him I’m afraid it’s not up to you where he takes him. I’m saying this as a lone parent. Just drop the rope with this loser.