Kate, you've gotten some great replies from other SI members. I'm earlier in this journey than some of them, so hopefully this perspective adds to the input you've already received.
My experience at 7 months out is that when I feel the pain, I'm not sure it is any less than it was at first. If I think hard about my moment of discovery, or those first few weeks, or about the relationship my husband had with OW, it hurts just as much and I can still find myself unexpected in tears. But...the great news is that the moments when I feel this pain are definitely fewer and farther between than they were in the first couple of months.
As others have said, the journey isn't always linear. For me the first two months I thought I was doing well, but in retrospect I was just numb. Then...once my husband decided to end all contact with OW, I thought I'd really move past the pain, but the pain actually got far worse. I think that my husband's taking active steps to start R and make me feel safe allowed me to feel the pain that I'd been suppressing for the first two months. So months 3 and 4 post-D-day were a living nightmare.
Eventually I decided that I would need to throw myself into R and to do so, I'd need to feel the pain but also be willing to let go of it once I'd felt it. Since then, I think about the A every day pretty much during every moment that isn't occupied with some other mental activity, but it's more something that is just there and part of my life. What actually triggers the most emotion in me now is thinking about how great my H has been these past few months and how much better we're doing and how much stronger our relationship is. It's not exactly tears of joy, but the strangest positive things trigger me like crazy and I turn into a sobbing ball of emotion. I'm counting my blessings and definitely prefer this sobbing to the sobbing I was doing right after D-Day!
Good luck to you and hang in there. It does get better.