Sleep Regression/Separation Anxiety Help

For the past week or so my boys sleep has been deteriorating and it's seemingly worse than ever tonight. He's usually a really good sleeper but for the past 2 weeks he's been waking up once at 3am every night (which is fine, it's only once) at first I thought it was for milk but he didn't really show much interest. Then I realised it was just for comfort, he would fall back to sleep the second I sat down with him in my arms. I didn't think much of it but it's gradually got worse. He started to wake up at the usual 3am and fall asleep in my arms, but it got to the point where I couldn't transfer him. The second I put him down he'd just cry until back in my arms again, then he'd be out like a light. It's gotten to the point where all week I've ended up co-sleeping with him from 3am onwards. For the past couple of days it's gotten earlier and earlier in the night. Last night he woke at 3am and wouldn't go back to sleep again until 5.30am. Tonight, he went to bed at 7pm and has woken up every 20-30 minutes since. It's exactly the same, he wakes up, stands up, cries. Falls straight back to sleep as soon as I pick him up. I can transfer him but then 20 minutes later it just repeats. He won't even accept his dad soothing him, he just cries until I'm the one holding him. I don't want to keep co-sleeping each night because I can't sleep well knowing he's next to me, and also I feel like I'm reinforcing the separation anxiety as he's going to get used to sleeping in my bed? I'm back at work now and will be working all weekend. I'm exhausted I don't know what else to do he seemingly just wants me to hold him all night but the fact he will only settle for me and not his dad also makes it harder🥲