Advise please !!!!!!

Ok so about a year ago i cheated on my fiancé ive always been insecure so when this hot guy was all over me i felt pretty and i went along with it we had unprotected sex and i never went to get checked out im affraid i might get news i dont want to hear because i am still with my fiancé :/ and also recently i went to one of my co workers house and we made out (didnt have no sex) i feel so guilty i mean i love my fiancé and i would love to spend the rest of my life with him but sometimes i feel unwated around him and do these regretting things advise please