We do Taharat Mishpacha and I'm totally an open book about it. I wish that more women in the community would be, actually, because it is such an important and beautiful mitzvah and even though it is very personal to talk about the inner workings of your "sex life," it is critical that we learn and get good information from other women who have btdt and lived to tell about it.
That being said, and I want to say this as gently as humanly possible, you are not under any halachic obligation to go to the mikvah whatsoever because your husband is not Jewish. Furthermore, if it is something that will make your husband upset and cause marital strife, well I'm not saying DON'T do it, but since you are not under any halachic obligation to do it, then it seems that causing a chink in your shalom bayit over it may just not be worth it.
I also want to say that as a religious woman who comes form a "mixed marriage," (meaning my father is not Jewish and my mother is) I understand and respect the need to preserve your Jewish hertiage and also the sancity of the marriage that you are in and it gets very muddled in the religious community when those two things seem to conflict.
That being said, I am so happy that you had a healing experience from the mikvah and if it is important for you to go on a regular basis, then I absolutely encourage you to do so. How you choose to keep TM will be, halachically speaking, totally up to you, as you are not required to keep any of it, so I think you can do what you feel comfortable with and create a lot of grey area so that your husband can come to accept and even support or encourage it and not feel as though it is causing any harm or inconvienence to him in any way.
You may just choose to have total contact with your husband but avoid sexual intercourse until mikvah immersion. You might choose to immerse the day after your period, or you may choose to wait until the halachically prescribed time (though you are not REQUIRED to do this, provided that your husband is not Jewish) to immerse. You could contact your local Chabad House and have a heart to heart with a rebbitzin there about it and maybe she can give you some ideas and insight about how you can keep the tradition of mikvah in a halachically appropriate way to your situation. For example, my mother (again, married to a non-jew) was encouraged to immerse prior to Yom Kippur, once a year. Many will be in agreement that you do not need to say the bracha upon immersion...and many more will say that it might be problematic for you to say a bracha at all, because it is not a mitzvah that is incumbant upon you and therefore you have no mitzvah to fulfill. This is no matter, though, as I have gone to the mikvah myself for reasons NOT related to the halacha of Taharat Mishcpacha (say, immersion in the 9th month of pregnancy, or pre shabbat or chag immersion) and I am also not required to say the bracha, yet I still reap the benefits of dipping in the mikvah waters and feel nurtured and healed by that.
So, first, I would recommend that you talk with an expert (a Chabad Rebbitzin is a good start) in HOW you can do this, hopefully without judgement and only in the spirt of love and encouragement, and then you can decide exactly HOW you would like to keep TM.
I think it's just wonderful that you are doing the work and effort to go and please remember that if someone expresses a non supportive attitude about you going, seek a second opinion. I would be happy to put you in touch with my rebbitzin in San Francisco, if you would like some gentle and helpful guidance, if your local Chabad or other resource is unable to provide it.
So thrilled for your positive healing experience!