I’m sorry you are going through this. You are a bit in the situation of someone who is overcoming an addiction to food; that is, it is not up to you to forego sex when you are married to someone who reasonably expects a mutual gift of life that normally includes sexual intimacy. That gift is part of the life of your marriage, not just recreation for one or both of you. You have a gift to give, as soon as you are able to give it, a gift that belongs to your husband, and belongs to him by virtue of your sacred promise. That does not mean you have to give what you do not have, but that you ought to want to be able to give this gift, and to make it possible to give it.
See someone professional about your problem, including helping you to figure out how to have your husband help you through it. I would suggest that you start with a conversation with your pastor, although this is work that will undoubtedly be long term and done with someone other than him. You’ll want his help in finding a trustworthy counselor, because there are those out there who will not lead you rightly.
I do not know if your husband knows about your past infidelities, or if those were committed against him, but you also need pastoral counseling concerning if and how you ought to divulge your past to him. Sometimes the victims of our sins have a right to know they have been victimized, but sometimes a confessor will conclude that to divulge the offense would itself be an additional offense. In any case, when we are married and sin against purity, we sin against both our spouse and God. Most of the time, the errant spouse has to discern the right course when it comes to admitting their wrong to their spouse. Sometimes, our spouse has made it very clear that they expect to be told everything, if we stray, or that they want to be kept innocent of wrongdoing and only expect total amendment and contrition, but those situations are very rare. Do not decide this by your own lights; get pastoral help! Remember, too, that the answer will depend on what is in the interest of your spouse, not what makes life easier for you. More than one opinion is not out of place, if you have any doubts. Arrange a special meeting with your pastor/confessor, because you’ll want more time to talk it over than you ought to take during the time scheduled for confessions of a more straight-forward nature.