When I got married, I felt like I was with someone who was way out of my league. When the alcoholism got bad, then worse, then really, really bad I stayed in the relationship. There were lots of reasons for that, but one of them was that I didn't feel like I deserved better.
After 28 years, my spouse went into rehab (and has stayed sober since, thank god). By then, I had also hit my bottom. I consider myself lucky to have found a group (Al-anon) that promised to love me until I could learn to love myself. I took advantage of that and discovered I love hugs! My family didn't do hugs. Mostly still don't.
One of the things I started working on immediately was "self-care." I had really neglected myself. Maybe partly because I thought my spouse should have loved me more than the alcohol (and I resented that she didn't), certainly partly because I was so focused on my wife's addiction that I didn't have time for myself, and partly because taking care of myself felt selfish.
If taking care of myself was selfish, I spent a lot of the next 4 years being "selfish." Time well spent. I grew mentally, emotionally & spiritually. I became and am becoming a better person. A better parent and grandparent. Progress.
Keep up the running, and whatever else nourishes you! My experience is that it helps to be part of a community of like minded folks. Maybe for you that's here. Maybe its a running group. It helped me to learn that I didn't have to do it alone (and I was such a loner)!
My very best wishes on your journey.