Terribly lonely, feel so low, suicide?

That is a common feeling in your situation. I would say that you could present couple's counseling to him as an option and if he declines that, then he obviously doesn't care about saving your marriage and you should just let him go. There are plenty of other guys out there who might be better for you anyway. It is similar to a first love scenario....we all have a boyfriend who is our first love. Once that relationship ends, we think that that guy was the best and we are never going to find another guy like him or better than him...you need to realize that if your husband is having an affair or has his eye on another woman, your relationship is not going to work. Try the counseling thing and if that doesn't work, I would say go through with the divorce.