Football requires focus and confidence. So do most other jobs. Lose your focus in football and you get steamrollered. Lose your focus in your average job and you could get fired. Just ask Quentin Jammer how going through a divorce can affect one.
Jammer had a terrible 2011 season. One reason he gives is that he was going through a divorce. The drinking he admits to probably didn't help either. But the divorce probably triggered everything else.
A divorce is a highly emotional time. You are splitting from the person you once loved. All that love and sense of lost (even if you want the divorce) get all caught up together. It is a rough time. In the meantime, you are expected to function normally and get through every day life. Sometimes all you want to do is scream.
These are normal emotions. What you can't do is let them overwhelm you. You can't dwell constantly on the lost. Or your current feelings for your spouse. If you do, you will lose focus. You will lose confidence. It will definitely make a bad situation worse.
Get help. Talk to a professional. Do not natter on to your friends all the time about it. First of all, they are not professionals, they cannot give you the advice you really need. Also, if all you talk about is your divorce, your friends will soon get sick of being around you. Then they won't be your friends anymore and you will be alone. Again, a bad situation made worse. Definitely do not post each and every feeling you are having to Facebook or Twitter. The whole world does not need to hear the intimiate details of your life. Your spouse's lawyer will have a field day with the posts.
Accept your feelings as normal. If you find yourself unable to cope, get professional help. And hang in there. Time heals all wounds.