In reply to your statement it is very well possible that Saul (Paul) was at the crucifixion of Jesus b/c it was the Passover so at the very least he would've been in Jerusalem, and since he was a Pharisee, as you pointed out, this would have been the death of all deaths for him and his parents as his father was also a Pharisee. Now I know that we could never say exactly whether or not he was there, but the likelihood is overwhelming, and as to why he might not of mentioned his encounter at the cross. If you would have been all for the killing of a man you just found out to be God and then went on to kill His followers for years would you have written about it?
No way!Some things are best left unsaid.