Even though your husband cheated and lost your trust you still have a lot of love, affection, and history left between you and it is difficult to throw all of that away over one bad choice. Your husband has to prove to you that he is sorry and has to be reassuring that it will not happen again, he has to prove to you that he has self control enough not to let it happen again. Cheating can destroy your self esteem also and make you feel like there is something wrong with you that made him cheat, often times the wife feels as though if they changed something about themselves their husband would not have cheated. You wonder what you did wrong, why he found someone else more attractive than you, and is he lying now when he says he still wants to be with you? Often a woman who has been cheated on will be left thinking deep down even if she doesn't realize it that she is not pretty enough, alluring enough, smart enough, or young enough to keep a man. Try not to obsess about what the other woman had that your husband found so irresistible that he had to cheat to get it. These are some of the have to reasons why you cannot completely trust him.
In order to make your marriage work your husband has to do alot of work, he has to tell you where he is at at all times so that you don't start thinking he is cheating again and he has to make you feel unwanted and appreciated again, he will also need have self control when it comes to other women and not want to commit that indiscretion again. You on the other hand have decided to forgive him and try to move on from this so that means asking the questions you want answered and then once you get those answer move on. You cannot continue to go back to the past once you have decided that you want to move on from this or else it will stir up old hurtful feelings and then you really won't be able to trust him. Make sure your husband's actions match his words. you may want to consider marriage counseling or talking to your clergyman about his infidelity and how you can make your marriage stronger from it.
It won't be easy and it won't be overnight so even though you want to trust him it's not going to happen right after the affair and you have to see some changes in your husband's behavior for you to even be able to try to move pass this. Allow yourself that time to be angry, hurt and cry if you need to don't live in denial that nothing happened in order to move pass the affair that will only make you more angry because you couldn't get your true feelings out there. Allow yourself to feel the normal emotions that comes with being betrayed by someone you love and who is suppose to love you also. Don't blame yourself for what your husband did or feel you need to change yourself to make him happy, he has to be happy within himself to make someone else happy so he has to take a look at why he did it and what he needs to do to make it not happen again.
You're welcome and I hope this can help you get your marriage back on track and if you need my help again I will be happy to help. Good Luck!