Crying after losing virginity?

Last night my bf of a year who I trust and love so much, and I, had “sex”. He put it in for a split second and i made him take it out immediately. Due to the sudden and intense guilt that I felt about what we had just done, I then proceeded to sob uncontrollably for an hour due to the shame and guilt I felt. There’s not a religious bone in me nor my families body. My parents are hippie liberals, and sex positivity is something I have been exposed to growing up. I thought I was ready. Is this a normal reaction? Why did I react like this?