I think my friend is being abused. Advice please? :(

So my boyfriend suffers from pretty bad depression, and he's recently been getting a lot more care from his mental health team. We realised he was Vitamin D deficient and iron too, and his GP is quite worried about the fact that it's probably caused by him staying indoors and not eating enough. She suggested he get out in the sun and try to exercise some more.

The thing is, he currently only has 1 friend who lives near us as we moved recently, and that friend (I think) has an emotionally controlling partner. His friend, who I will now call Jack, and Jack's girlfriend (Emma), are never apart for longer than a couple of hours, and this is difficult because my partner wants to go out with Jack more regularly and do this together as like two guys hanging out, but she's either always there, or always at the end of a phone to the point she might as well be there.

Jack has been in an abusive relationship before, and everyone thought his partner was perfectly normal, until it came out that she has tried to physically hurt him with a (butter) knife, and that was the last straw for him.

To give you an idea of the level of control Emma has over him: she somehow monitors his spending, she constantly voices out loud what he is and is not allowed to do 'youve hade three cigarettes today, that's your allowance' in a jokey way, but then has proceeded tto pull his hair quite tight if he does go to have another. She chops and changes her rules all the time, so it seems he never knows what might or might not piss him off. She recently said to him that she could find anything out, and that she was probably more skilled at it than the police, and that she's omniscient like God.

She's quite openly controlling (but she does this in a jokey 'im the pants-wearer' way. I know this could be nothing, and it could genuinely just be a little quirk of theirs, to act humourously nitpicky toward each other in front of people, but what worries me is that when he is (rarely) alone, he's always saying she'll be mad if I'm late (the other day he was at our house and she was coming to pick him up. Her car pulled up outside and he was visibly jittery and jumpy, saying 'Emmas got this thing about me not leaving her waiting more than 30 seconds. It really freaks her out'. And he's mentioned (jokingly) before that she has an expected time limit on how long it takes for him to reply to a text).

As I've said, she makes all this stuff seem jokey and fun, but I don't buy it, and it seems like he compromises a whole lot while she doesn't at all. It goes as far as trying to make him do things that he should literally avoid, to show appreciation to her. Like yesterday, she'd made him a daisy chain necklace and have it to him as we arrived to meet her and her friends, and he said 'oh thanks, but I have hayfever', and then she started shouting in an exaggerated pantomimic way: 'ohhhhj see I told everyone you'd say that. I said watch me make this and Jackll complain that he's got hayfever'. So he put it on and wore it for hours to appease her, despite suffering also from asthma so it's not like a minor inconvenience.

She also controls what he can eat, and jokingly says he needs to lose weight, and is generally building a life plan for him - she makes him drink a certain amount of water, and yesterday, she just randomly came out with 'jack, your armpit glands look swollen', when he was lying down and relaxing outside on the grass, with a t shirt on that covered his armpits! Should wouldn't drop this, and kept saying it's because you're unhealthy, you must've done ....'

I don't know what to do, because my partner needs his friend around him right now. He would really benefit from having someone he can hang around with at least one day a week, but every time they plan something, she seems to be a presence somehow. Like, yesterday, he asked his friend 'do you have any plans today?' and Jack said no I'm totally free, so they met up for a drink, and had plans to go for a long walk back to our flat to then have food and chill out. Within the hour, Emma was on the phone saying she's planned a BBQ and he had to be there by 5pm (it was now 3.30). I told my partner to take the initiative to muscle-in at this point, and say 'oh that sounds nice, what shall I bring?' and so he did. We both went, and when Jack said 'we're going to get another drink and then make our way there then. She gave him a long list of stuff we had to get at a supermarket for it, meaning that our time to have a drink was totally limited.

Can anyone give me advice? My parents were in an emotionally abusive and sometimes physically abusive relationship when I was growing up, and I now suffer from cPTSD because of it, so I worry that I am just being paranoid, but I don't think I am.

I want advice on how to handle her behaviour toward him when I'm around because at the moment, I just laugh and dissociate quite a lot because I am really uncomfortable due to my past

I'd also like some advice on some things my partner and Jack could do together that would minimise her involvement. I suggested them going to see an action film at the cinema (not her taste), and my partner wanted to do something like grab food and a drink with him after, but hadn't mentioned it yet. Jack said he was free all evening, so he didn't feel the need to plan it with him in advance. Near the end of the film, Jack was texting her back during the credit scenes, and when they were leaving he announced that she was apparently having another BBQ that evening, and she just happened to be in the supermarket next door to them (on the other side of the city from where she lives) shopping for it. Jack invited my partner to it, but without Emma present so he felt it wasn't right to go, and then when we saw them the next day we asked how the BBQ went and they said 'oh we didn't do it in the end because (so and so) didn't turn up'...

I'm just at the end of my tether with it because my partner seems to be being blocked from spending any extended amount of time with his friend, and I have to keep watching how much detail I give about things we've done together when I'm around her. Like the other day me, my partner and Jack met up in town, and then met her an hour later, and I found myself talking about what we'd been doing, omitting details like going to McDonald's because I knew she'd freak out about how he's spose to be eating healthy.
I know she suffers from anxiety, and is seeing a therapist, and he often gives this as an excuse for her behaviour ("I guess I don't have to deal with worrying about stuff in the ways she does")
But what is odd is that she's a social worker, so she's been educated on abusive relationships, and I've spoken to her about my own father's abusive behaviour toward my mum and she nods along and comments on how 'emotional abuse is sometimes worse' ...

Has anyone got any suggestions???

TIA