Your trauma was pretty recent so please give it time. I promise things get better and will share a bit of what helped my arc of healing.
First, I did a little OLD, which worked out pretty well but I found I was in no mental shape to have any kind of relationship. However, I mention this only because sometimes it did help to get dressed up and go somewhere and met someone for coffee or a drink. Admittedly, I was in sore need of validation and found it -- don't recommend this for everyone though.
I also created a playlist of songs that helped me get through rough spots. I would put on my headphones and walk or run -- each playlist had a theme -- resilience, reckoning. The music helps re-wire the worry and anxiety brain -- not to distract you from it, because it's important to lean into those emotions, but to help you push through it. I also unearthed music from decades past -- the 1990s, 1980s, and remembered a bit of you I used to be. Also, keep moving, exercise, walking, lifting weight. Somehow the weird stuff gets manageable when you are moving.
I also did some travel, took road trips and traveled by air to different spots before the world shut down. The road trips are easier in a pandemic and there are so many cool towns I explored. One of my best days of healing was when I flew to Gig Harbor in Washington state and stayed in an airbnb. I read and slept for 14 hours one day. I was emotionally exhausted.
I struggled a bit to find my passion for hobbies I have been pursuing since a kid after my divorce, so took a bit of a sabbatical from them. I didn't know myself anymore because my identity was largely from my marriage and our lifestyle. In the meantime, I tried to discover new things -- took Italian lessons through Skype, planned a trip to Italy which was cancelled due to the pandemic, now taking a writing class. When I was ready again I took up my old hobbies and am finding my passion for them coming back. It just took time -- time is your warrior.
It might seem like xWH is living his next step but I found that cheaters deflect and avoid their guilt and shame and compartmentalize. It's easy to think they are doing better but try not to compare your lives. Infidelity is the language of the emotionally stunted. I can't imagine that your XWH has any more emotional insight than my XHW. HE's still with OW and so diminished by what he's done. 4 or 5 years ago you will feel joy and what has happened won't rent so much space in your head.