OP so in the past your husband has flirted/behaved inappropriately/had an affair/all of the above? That's what you seem to be intimating.
And you want to stay with him because you've 'been through so much together'?
Have another look at cinnamon's post concerning 'Sunk Loss Fallacy'.
It's like a gambler pouring more and more money into their addiction because they've lost too much to stop now, they have to make it back, there must be a big win around the corner....
Why put up with it? Either you can have:
a) difficult past with continuing difficult future full of paranoia - if you stay with him
or
b) difficult past with no more paranoia or worry, the chance to focus on your own needs, the possibility of meeting someone respectful, faithful and supportive - if you end the relationship.
You can't change the difficult past bit. You can only decide, now, whether you want a future filled with more of the same. Or not.
They say that irrationality can be defined as doing the same thing in the same way but hoping for a different outcome each time.
It's so hard to make a break like this, when all you want is to share love and trust with the man you love. But you have to think, now, about the reality of your situation.