Maternity leave guilt

Friday was my last day of work for 12 weeks (having baby Tuesday). I was SO ready for that day to come as I was so tired. I am a teacher and left everything in perfect order with plans laid out for my long term sub. But since I got

home on Friday I have been feeling so much guilt and anxiety. Like 12 weeks is too long, that my students will not be successful without me, that my coworkers will resent me for being gone, and even that I may not be asked back next year. This hit me out of NOWHERE. Has anyone experienced this is or experiencing it?