Considering the enormity of death or divorce, your task is not to rebuild a whole life immediately, it is first to recover. Initially, your mind is whirling with fears. Decisions made in this state will almost certainly create more problems than they solve. Take some time to rest and let some dust settle. In a panic, many people rush into dating or financial decisions they later regret. Dedicate time to rest until it seems that you're thinking clearly again.
We cannot change our past. We can not change the fact that people act in a certain way. We can not change the inevitable. The only thing we can do is play on the one string we have, and that is our attitude. Charles R. Swindoll
Once you're less stressed you'll see many of the things that seemed to have changed have actually remained the same - only your world has changed, not THE world. You are still part of THE world and you can rely on that. I would highly recommend that the first active step you take is to invest in your own health and wellbeing by making sure you eat well and exercise. This sounds boring but your health is the foundation of all your capabilities going forward. If you had a broken leg, you'd do all you could to support a healthy recovery, you wouldn't rush out and learn salsa dancing, which would only make things worse in the long run.
Taking care of yourself will then increase your confidence which is what you need for the next step - making healthy friends. Some of the friends you had when you were married will be lost and this is a chance to make new ones. After health, we rely on our relationships for support. Choose friends wisely - avoid the complainers and be with the people who're happy and successful - their view of the world will rub off on you.
Next, find a worthy way to spend your time, whether that's work or a hobby. We gain self-respect and meaning from the way we occupy ourselves. Without those we are even more bereft. Find work with an organisation doing good things, volunteer for something worthwhile, enjoy a hobby that improves your skills at something. There is a whole world of opportunities you may never have noticed before. You can discuss all the options with a friend who may be able to see potential in you that you cannot see in yourself.
The trick with anything in life is having the right perspective. Don't rush into things, take a moment to step back and notice what's in front of you. There's always more to see than is apparent at first glance. Also, there's always more to know than you currently know so, do a little research on any decisions you're working on - better decisions come from better information. And don't fret over decisions - you're allowed to change your mind on anything at any time. Make small decisions and see what happens.
Overall, the idea is to make a little progress all the time. Grief and recovery is a process, not a place. You're balancing the need to take your time with the need to keep moving forward. Each Sunday night ask yourself, what have I done this week to move myself forward? Make sure you have at least one answer to that question.