Hi Sam
My long term relationship/marriage (19 years) ended 3 years ago so I can relate to what you're going through. The good news is that it does get better and I've come out of a really low period in my life; coming up smelling of roses so to speak.
A few tips. Please don't think that I'm trying to tell you how to live your life. I'm not. But if you pick up one thing from my experiences then the time that I've spent thinking about what to type and actually typing it will have been well spent.
Find someone you trust to confide in/share your fears with. I was lucky to have my brother who was always there for me. He'd been through something similar. He was my rock.
A decent solicitor goes without saying. Remember that the law says divorcing couples are entitled to part of pension funds etc. Try and reach an agreement as to who has what without the solicitors bearing in mind that there is hardly any value in second hand furniture!
Try and keep matters as civil as you can with your ex. Being stubborn/bloody minded gets you nowhere and generally means more solicitor involvement and more cost.
Don't put a brave face on things. You will feel really low and the whole divorce process is an emotional time. I went through a period of mourning for what my ex and I had. The day the final paperwork arrived from the courts was quite surreal. An official piece of paper that replaces your marriage certificate and states that you are no longer married. I'm not ashamed to admit that I cried when I looked at that court notice.
Going out on the pull is an interesting one. The male ego being what it is means that we think we're still attractive to all women regardless of age. We're not. I'm guessing by the 66 part of your username that you're in your 40's or maybe approaching them. Ask yourself whether you want to meet a girl in a pub/bar.
When you feel ready, get back into the dating thing. Don't make the mistake that I did and talk about your ex on a date. bad move! I learned that very quickly. It's an instant turn off. Your ex was a major part of your life for 20 years, it's natural to talk about her but not on a date!
I thought that I would be the only 40-something singleton out there. I wasn't and there are loads of people in a similar situation.
I said at the start that I'd come through a very difficult period in my life. I've moved on and I am now married to the most amazing woman who gives me what I have always wanted from a relationship. Marriage is so much better second time around. I love her madly and and times we're like a couple of teenagers. We met via an on-line dating site and they really do work! I can personally recommend Match.com. Loads of people use sites like Match and it really does work.
Be happy, be positive and above all move on in your life when you are ready. It is going to be a difficult period in your life but it will not last forever.