We have all pretty much been there at some point. That relationship where you just got hurt cause you foolishly let your guard down and now its up and 10 times stronger, but you feel like your new spouse is being hurt and you are being hurt too. You dont wanna punish him or her for your past but at the same time no one likes re runs.
Here is the tricky part. You wanna incorperate your past but not to the point where it hinders the growth of your future. Remember the lessons you learned from your ex but dont punish your current spouse for them. Be alert but not paranoid. Dont treat your spouse as though he or she did something wrong. They are innocent until proven guilty, not the other way around. It will be hard to trust and be open but thats okay. If your partner is able to understand that you are hurt and is willing patiently wait until you are healed and help you with the process then the least you can do is try a little too.
On another note, you dont want the desire to trust to make you blind to obvious signs. If your ex cheated on you and you suspect our current partner is doing the same dont ignore it under the idea that "oh this is Jane and shes nothing like Sally". Dont ignore the signs but dont go looking for them either.