Trust

So how hard is it for you to trust?  I know for me it seems to be too hard.  My hubby has become somewhat of a Facebook junky.  He says it is to keep in contact with all of the people that he went to school with.  Now am I crazy or where there any boys in his class.  And why does he always have to send them messages and instant messages.  All the people that he friends are women.  Sometimes it seems as though he is flirting.  He has been caught being inappropriate with other women before, a few times.  I know I am supposed to forgive and forget.  It is just so hard for me.  I pray that God will help me to trust.  Trust is so hard to give back once it is lost over and over again.  I wish I could get my hubby to understand where I am coming from.  I do not want him to give it all up, but I have asked him to keep the conversations public by posting on the person's page or what not and yet he still sends messages and chats.  Will I ever trust him fully again?