Being a Christian is not a visa to never sin, in the sense that we are sinners, heirs of evil through our adamic nature, and this leads us to make mistakes on a daily basis, to do things that we do not even want to do (see Romans chap.7). And moments like those many times lead us to “guilt”. Yes, to feel guilty, and this feeling guilty is right, but the problem is when we believe that God will not forgive us for it.
Many people have ever made a serious mistake in the way of the Lord, and have preferred to distance themselves from God because of the shame of what they have done. It is true that sin is sin and the Bible condemns it again and again, but the greater crime is not to sin, the greater crime is to remain in sin (1 John 3: 8).