How to build up trust

my husband and i have has some problems recently with him being unfaithful i have had him back but i dont trust him and dont know how to build it up again.he works near this woman and she has a lot of problems with drugs and debts and i think they are still in contact but he denies this and i have no proof, this woman his his ex.we have met up and she told me that they slept together which i believe he even took her away for a night and he still denied sleeping with her does he expect me to believe nothing happened?i want to move on but my head is messed up i wanted him to be man enough to admit what happened but he says nothing sexual happened,i suspect him all the time if his phone rings if hes late home from work etc ive even sat in the street where he works trying to catch him out which i havent, do you think hes learned his lesson , and how do i forgive and forget?

no he hasn't learnt his lesson. By the sounds of it he still hasn't told you the truth and until he does there is no way your marriage will work. If you are still so suspicious then he hasn't exactly put your mind at ease...why not?