My SO has a chronic pain disorder. So, I'll try to relate my experiences as the SO of person with a chronic illness. The exact cause is known, but there really isn't much to be done about it. I'll skip the specifics of the disease, but suffice to say, it is on the cusp of being classified as a 'suicide disease'.
For my SO, it's a day-to-day thing. Sometimes it goes down to minute-to-minute. But there is always another minute and another day with less pain. Keeping focused on the good days seems to help my SO.
Spirituality and religion have had mixed success. Spirituality has helped more than religion, so to speak. Organized religion may be good for some, but we have not had luck in finding a community that helps my SO. Church folks kinda get gossipy and start expecting things of my SO that my SO can't provide during painful times.
Love and support from friends and family have been essential to my SO. Limiting contact with family that is non-supportive has been good. Surprisingly, covid-time has been a boon on this front. Find people that actually support you and be quick to limit contact with unsupportive people.
Staying up to date on the latest medical new has been mixed. One can obsess over the newest studies. So we try to look into it about once avery 2-3 months for anything new.
Support groups have mostly been a wash. Online groups tend to be mostly people that are new to the disease. Over time they come to accept the diagnosis and the restrictions on life that come with the disease. But it can be tiring trying to help people still in denial. They also tended to become ... well ... suicide pacts, at least with my SO's disease. Keeping a good eye on your media consumption is essential.
Real Life support groups are hard to find as my SO's disease is pretty rare. We've gone to support groups for related diseases and those did help my SO. But as they were for a related disease and not my SO's, they were of limited utility outside of human connection.
Life expectations have been readjusted. It's not an easy process, and you need to give it the proper time to grieve. The grieving process takes as long as it takes, but you must take it. Finding new goals and dreams in your life is an important part of this. These goals must be meaningful and achievable to you for them to be effective. It's really hard to meet both criteria if you've not finished mourning your past conception of your life.
I'd be happy to answer any other questions as well. Good idea on reaching out and trying to get some help. I know that is a tough step to take. Your courage to do so is inspiring!
In general, my SO takes every day as it comes and we have to accept the realities of our lives as they are. It's not easy, but it's a lot easier with friends and family.