Will they be mad at me?

Ok so six months ago I took a part time job. I told them i’d be able to go full time in three months once i’m done with school. life happened, I experienced some losses in my life, and I ended up having to extend my schooling until now. im a month away from graduating and told my job that i’ll be able to go full time in a month. the thing is, is that now that i’ll have a higher degree… I could do so much better than this job. they are severely underpaying me. even if I got a raise, i would still be underpaid. im embarrassed to say how much I make as a professional nurse. I am a young person just about to start my life and I should chose better for myself. is it wrong of me to leave this job before going full time like I promised? I was thinking of lying and saying im moving. I just know they’re gonna be pissed at me and I have so much anxiety about it.