My SO told me that I'm selfish. I just told my boss that I need to go part time so I can be home…

My SO told me that I'm selfish. I just told my boss that I need to go part time so I can be home during the day and home school my seven year old who is struggling in regular school. I losing half of my income plus my benefits not to mention I have 6 days of vacation time I didn't use that I just lost. Not really sure how that is being selfish but ok.