I suspected you probably had back problems, too, and did a search and saw you had back surgery. I think your groin problem may be related to your back.
I hope, by the way, that your back surgery was a success. I had chronic back problems and, fortunately, discovered John Sarno's book, Healing Back Pain: The Mind-Body Connection. His belief is that herniated disks are harmless and that many people have them and have no pain. May sound crazy when you first hear it, but the book worked miracles for me. If you still have any kind of back pain, I HIGHLY recommend it. It changed my life.
In my opinion, assuming excessive stretching isn't the culprit for your long-term groin pain and that you have at some point rested it for a significant period of time, I strongly suspect there is a mind-body connection to your groin pain and that it may be directly connected to your back. I'll break down my thinking into two parts:
1. Sarno's follow-up book, The Mind-Body Prescription, applies the same theories that relate to back pain to ailments in other parts of the body. When I have any kind of injury that I have given a reasonable amount of time to heal and it hasn't, I refer to the tenets expressed in his book and then I begin my normal exercise routine and work through the pain (which he recommends). This has worked for many lower-leg "injuries" with the exception of my plantar fasciitis last year (which I was too fearful to trust would go away if I continued to run on it, but I suspect it probably would...acupuncture ended up working).
2. Oftentimes, when I get pain in my knee area or groin, I can, by pressure with my fingers, locate the nerve that's triggering the pain sensation. I then find that I can usually trace the nerve upward to some extent and find that there is pain at various points along the nerve. Therefore, my opinion is that the pain is really being triggered at the root of the nerve in the lower back and not in the groin or knee. I don't really know what sciatica is, but this might be similar to that. I then conclude that, though there is pain in the nerve, there is nothing seriously wrong with me (in accordance with Sarno's theories). There is more to it, that you'd have to read the book to find out, about addressing mentally why your body is reacting to psychological issues with physical pain. Keep in mind, the pain is real, the nerves are being irritated, your disk in your back may be herniated, but none of this should deter you from physical activity. You can make the pain disappear and you can have a completely normal athletic life with herniated disks.
You may find this stuff too far out there, but I urge you to look into it and give it a try, since your ailments very much seem to mirror my own.