We appreciate the sensitive nature of this question.
Given the situation, it is legitimate for you to make a personal decision not to immerse. Even if your husband insists that you go to mikveh, that does not halachically obligate you to do so.
That being said, not immersing means abstinence for an indefinite period of time, which requires both spouses working together to preserve shalom bayit.
It would be best if the two of you could come to a joint decision about mikveh, looking together at the materials we’ve made available on our site, inquiring about the precautions your local mikveh is taking, and talking out both of your concerns.
You may want to talk personally with a Yoetzet Halacha to discuss some of the halachic and practical aspects of working this out. As always, Yoatzot Halacha are available through our phone hotline or in the community. If you and your husband need more assistance in building healthy communication around this decision, you may also find it helpful to consult with a counseling professional.
May we all merit good health and good news.