I would try to find out from your spouse whether or not they have actually cheated on you as the insecurity and uncertainty is a death-knell for your relationship. It is better to know for sure if they have cheated and then you can work from there and decide what to do. If it is simply because you have a low self-esteem and low self-confidence, it may be that you are imagining things that are not there. But at the basis if all this it seems as if trust is a problem and that is something that needs to be addressed.
I am thinking the operative word here is “suspected”. Obviously, suspected and actual fidelity are very different, but not so much for the experience of the partner with the suspicion. That said, intuition is frequently spot-on, especially if you know your partner has cheated before. On the other hand, we can certainly have suspicions of things that are not happening. But if you are suspecting infidelity in your marriage, it means that there are trust issues that need to be addressed. Redeveloping trust is imperative for any relationship’s success. Some spouses go as far as to hire private investigators to help them discover whether their partner is cheating. This is too bad, since it means they actually have to sneak around to find out information rather than just having an open and honest discussion. The point is, saving a marriage with significant trust issues can be done, but it will take work. Counseling is a necessary pursuit in this type of relationship.