OP, if all this is true, what you have here is a bog standard open marriage...
Also, re you "having many relationships" - you were in your 20s, so how many was "many"? I doubt they were long or serious. Also, you would not be able to find anyone else while being emotionally attached to someone, no one else will compare. You need to separate properly, be on your own for a bit, date and then decide. I would imagine you are what, 35-36? With 4 kids I doubt you had time for many relationships except for flings.
I also find it strange that you say "there were many man who wanted to impregnate me" - wtf does this even mean?.. That's does not sound normal. What, there were many man who said "I will impregnate you but will not have anything to do with you"? How this kind of conversation would even happen?
You sound desperately in love with your husband, you put him on a pedestal. You sacrificed a lot for him. While all this time you denied yourself a fulfilling relationship with someone who would love you in a simple, non-complicated way, who would think you are enough, who would find you sexy and who would want to grow old with you. I get that this may not happen to many, but you did not even allow yourself to try and find this person.