Separation anxiety


So I just returned to work after 12 weeks of maternity leave and it has been hard. I dropped down to part time so that I wouldnt be away from my son for too long and while I’m gone he’s with dad. I’ve worked 3 days so far and it’s getting really frustrating. The first day was emotional because my son wouldn’t stop crying the whole time I was gone to the point his dad brought him to my job and he was shaking. Day 2,3 he didn’t cry as much but he still cried almost the entire 5 hours I was gone and he is inconsolable. He will calm down when I FaceTime him but once he realizes I’m still gone he goes right back to crying. It’s hard to be at work knowing he’s so upset and his dad is stressed and frustrated cause nothing he does comforts him. I’m now frustrated with him because the 20 bags of milk I had stocked up are already gone in 3 days because every time my son cries, he wants to pop a bottle in his mouth thinking it will change things and I told him prior to me leaving not to do that. He keeps pressing me to quit my job altogether to stay home with baby. He gives up too easily cause he just wants the baby to stop crying and he’s wasting milk in the process. Any tips to help dad and help baby with his separation anxiety? To also note, if he takes my son to one of my friends houses my son instantly calms. He seems perfectly fine when he’s with a woman or if their is a woman with there with him and dad but alone with his dad he flips out.