AITA - med spouse edition

My husband and I have been married for six years. We were both medical students when we met. At the time, he was not as attached to academic medicine/fellowships as he is now. We got married with the understanding that he would be very focused on his career and I would be more part-time, as we wanted to have a large family if possible. We have 3 kids under the age of 6 - two were born during residency and one during my first year of staff life. He did a chief year, followed by a fellowship in his subspecialty. I did a residency only and have been working as a staff physician since then. He finished his fellowship in July and is working very part time as a staff physician since then because he is putting most of his energy towards a masters degree. Now he tells me this masters will take up not a year as I initially was led to believe, but probably two years where he will continue to work full time on it and do some doctoring on the side. I am so upset and frustrated - I do the vast majority of childcare/housework/breadwinning. He is super tired whenever around our children or at home. I feel like he doesn’t like our family. He feels I am overly critical. We do have babysitting support and cannot afford to outsource anymore than we currently do. He has much larger loans than I do from med school. I feel like I’m married to a grad student now, but he feels he could not do academic medicine without this masters degree. Am I overreacting to be upset?