I'm guessing you are posting in the wrong place. Our organization supports straight people who find themselves in a relationship with someone who is LGBTQ. There are no doubt many resources for someone in your position, however this is not one of them. I hope you find what you're looking for.

My ex is a MTF trans femme and has transitioned with hormones & orchiectomy.  I am No Contact.  
I went to his Trans Clinic appointments for 3 yrs with him.  Believe me that they do receive plenty of specialized education about their physical, emotional, mental health as well as resources available.  In addition he went to four different trans support groups in our state and was well educated/informed and supported.  Let me say that there was NO support available for me, as far as how this was impacting me, I guess I was expected to adjust to his changes and was invisible although I indeed did have a 20 yr relationship.  I felt like I was chopped liver.  And how great and brave he was to be his true self, a woman.
JEEZ, all the emphasis is on the trans person. Good luck finding any support for the straight partner.  I’m sorry, whether you are male or female, it’s a shock to learn of the sexuality revelation.  Think of yourself and your feelings.  There will be many changes ahead of your partner depending on how far they go with the transition.