We are sorry to hear about your difficulties getting to mikveh.
We understand that this is a difficult and frustrating situation, since resuming contact prior to mikveh immersion is prohibited and the clean days cannot be shortened. It is altogether natural that over two months of limited physical contact would put a strain on your relationship. If there is any chance of your husband delaying his trip or coming back sooner (or your joining him) then that should be explored. But if that is out of the question, the two of you will have to find a way to cope with an additional delay.
You cannot control or take responsibility for your husband's reactions, but you can do your utmost to improve the atmosphere over the next few days. Be understanding of your husband's frustration and make sure to express that your actions are guided by halacha. Ask your husband or anticipate, based on experience, what steps you could take to help him manage the strain better going into his trip. Although physical contact plays an important role in enhancing shalom bayit and improving our ability to handle strain, there are surely other resources in your relationship to draw on to improve matters. Instead of focusing on what you cannot do, work at doing whatever you can.
Please get back to us with any further questions.