First, at 2 months out, you're probably still in shock, reacting to the trauma of D-Day. Many of the things you do today are simply not the new you. You'll start to get control of yourself soon - maybe next week, maybe next month, maybe a couple of months - whatever it takes, lots of your behavior now is temporary.
Second, obsession with the ap is common. The fact that you know it could be a problem makes me think you'll stop within a reasonable amount of time. My guess is you should post about this again in 2-3 months, if you're still concerned - only because obsession might be, but probably isn't, a problem 4-6 months out.
You probably focus on ow so as to avoid feeling your own grief, rage, and/or fear from being betrayed. When you start to check up on ow, it might be beneficial in the long run to check your own feelings. My own experience was that focusing my anger on ow allowed me to hide my anger at my W - and after all, my beef was with my W, not with ow. It's highly probable that ow seduced my W, but that doesn't mean ow is to blame. After all, my W could have said 'No' at many points.
Healing comes from dealing with your own feelings, no matter what they are, and with your relationship with your H. WRT recovery and R, ow is really irrelevant.
Third, have you outed ow to her BF? He really deserves to know, if only to know that he needs STD testing. Alas, so do you and your H. (In truth, I just made my W get tested. Since she's negative for everything except HPV, I've skipped it - I just don't want my doc to think either my W or I have heated.)
Welcome to SI. Sorry you're here, but since you've been cheated on, I'm glad you found us. There's lots of support available here.
A note - It's up to you to choose what to do with the counsel you get from SIers. You'll get support here, whether you accept or reject the advice you get, and I don't think I've ever seen an 'I told you so'.