Thank you for reaching out to us.
We appreciate the sensitive nature of this question, and are sorry to hear that mikveh nights are so difficult for you and your husband, and that he is not supportive in general of your niddah observance.
We appreciate your commitment to observing these halachot even though they have become associated in your marriage with stress and separation. Rest assured that keeping these laws has independent value, just like observing any mitzvot. 
If we understand you correctly, your husband finds mikveh night upsetting because he does not want to have relations dictated by a halachic calendar. (Please correct us if we have misunderstood.)
Although there is halachic support for having relations on mikveh night, it is not strictly obligatory. A couple can agree to postpone them.
Perhaps some of the stresses and fights could be alleviated by letting your husband know that you have immersed, but that you dont need to have relations until it works well for the two of you.
With relations less of a stress on mikveh night, perhaps you could refocus and find a different way to enjoy the evening together in a way that builds your feeling of connection. This might also leave room for looking more clearly at any other ways in  which observing these halachot have been a challenge, for either of you.
If you find that the issues go beyond mikveh, you might find it helpful to seek out professional counseling. Referrals to religiously observant counseling professionals can be found at nefesh.org.
Please let us know if we can be of any further assistance.