Fiances bm wont let him see his kid ❌ PLZ HELP

When me and my now fiancé met he was fresh out a relationship with his bm so fresh she thought they still had a chance of getting back together but he was done done . She was pregnant and they had 2 kids together already but she had cheated on him several times till he was done . He was still going over to her house visiting and dropping off stuff for his kids etc . When he made things official with me . He told her about me she was mad but said they could coparent . Hed meet with her in public weekends from noon to 4 pm to see his kids . That lasted 2 weekends becasue she found out we moved in together then she started DM me on my socials accusing him of cheating on me and stuff however he had already told me everything that they did / talked about after every visit plus I had his location showing he never went anywhere private with her. (Parks, kids museum, water park, baby store, etc) He told me how she asked for them to get back together and asked if we were serious or if he was just having sex with me becasue they ofc had a baby on the way and he told me how she planned a lot of stuff for them to do together as a family like they were still together but swore he never touched her in anyway except for feeling the baby kick or whatever and blocking someone from running into her .

When she realized she couldn’t get in my head to leave him alone she Took away his visitations he asked if he could just have his kids for the weekends she said no she also denied him having them for a couple hours a day . All becasue she doesn’t want her kids around me . Father’s Day she finally let him have the kids becasue he had to kiss her butt a lil apologize for leaving, promise he goin be in his kids lives and stuff . I ofc couldn’t be around which was fine . She dms me literally the next day and asks if I was around her kids . I didn’t reply . She gets mad and starts talking crazy So after telling my fiancé What she said I go off on her . She then takes his kids away again becasue “he let me disrespect her”. A few days later he makes a gc with me and her apologizing again saying that he respects her, that I have to respect her as the mother of his kids and she has to respect me as his gf. She gets mad that he didn’t send that to her separately. I apologize there too for going off on her and respectfully ask her to keep me out of they business. She agrees and tells him he can see his kids through FT . He’d all and txt checking in for a month or so then she finds out we got engaged and cut that from him says he can’t be at his baby birth and can’t see his kids ever again . They argued for a while his mom told him to give her time and space becasue it’s the pregnancy talking and she’s mad he gets to live his life while hers is on hold becasue she’s pregnant and maybe things will get better once the baby gets here. He’ll just have to play a waiting game . That was mid July . Fast fwd to today he txt her asking how his kids and the pregnancy going and if she could send him a pic of his kids . she says no they argue he says he’s done trying and not to contact him when the baby gets here and she laughs at the fact he can’t see his kids and says she gonna put him on child support and even had her brother threaten him over the phone . (All of this becasue she’s pregnant and still wants him )

So as of right now he hasn’t seen his kids in person since Father’s Day , but every weekend he has left money , clothes , diapers, wipes, food, gifts and stuff at her door . He has kept his receipts of everything since she started with the visitations months ago . Which after today he plans on stopping .

It’s driving him crazy he can’t see or talk to his kids. He’s so sad missing work staying in some days & others doing wild stuff with his friends.

WHAT SHOULD HE DO ❓

*got his permission to post this .

UPDATE :

He had it already in his mind he was going to leave long ago. She knew that . To answer one comment we both love each other so moving fast isn’t the problem y’all haven’t heard those stories a man will be with you 10 years not marry you and the next man with you 4 months and marry you??? Also her point of view she doesn’t want me around her kids becasue she’s not ready to accept them being over plus she’s pregnant