iaintfromkansas I can relate as I could of written much of your post. I too have been single since ds was born. After several years I found a new partner through an online site, but the relationship was toxic and he was emotionally abusive, and despite being a strong person it left me without any self confidence and not wanting to be in a relationship again. I stayed far longer than I should of because I felt I had to be with someone and someone was better than no-one. But actually being on your own and in control of your own life is better than being with the wrong person who makes your life worse by being with them. So try to remember that when you feel low or lonely; that you might be sad and lonely now, but you are better off than you were then and you have a chance for happiness now when there was little chance of that with him.
I also found that the few friends I had seemed more to be fair weather friends and the few I have left aren't in touch very often. I tried for ages to keep these friendships up as I felt I'd have no-one otherwise. But we have grown apart and I have now let them drift a bit and am far more choosy as it felt as if I was the one trying to keep it going a lot of the time and that can knock your self confidence too.
When you are already low it can feel as if it's you that is the problem, but it isn't.
I finally decided it was better to cut ties than to be unhappy and feeling to blame for these friendships drifting and that there was something the matter with me when people weren't in touch. People's lives, priorities and commitments change and basically they are more wrapped up in their own lives and worries/issues and don't have time more than anything else. It's nothing to do with you.
Despite my best efforts, while I know many of the other parents at ds's school and have tried very hard, none have turned into friendships. Though there are a few I do feel I could call on if I needed help and I think they would help if they could.
It's all very well saying get a babysitter and make an effort to go out, but when you can't afford to go out, let alone pay a babysitter, it's not that easy. One friend offered to babysit so I could go out. I said that was great but that it meant I wouldn't have anyone to go out with and I really wasn't up for turing up to a bar or pub on my own! Though I have gone to the cinema on my own occassionally. Not sure I'm going to meet many potential friends there though!
I now realise that many people don't actually have that many really close friends and I'm not the odd one out at all. The difference is that they have a partner for company and share their dc with. It's the not having anyone to call or talk to that is the hardest for me as a lone parents.
It has also taken several years but I am now getting my self confidence back. Time really is a great healer and one day you will start to realise that the corner has been turned and you are finding yourself again.
Give yourself time and try not to force things until you are ready.
Ds is a bit older now and I am finding it easier to leave him on his own for an hour or so in the day while I go shopping or for a walk. Evenings are still an issue though and I don't feel comfortable leaving him to go out for an evening.
I joined a lone parent group in our area a few years ago and have found what I hope is a couple of good friends through that. I did dispair at one point even with that, but stuck with it for ds as much as anything as he had company, friends and oportunities through that, and I'm now finding benefits for myself too. And if nothing else it gets me out the house for an evening once a month and there's no issue of can ds come along too.
Someone here suggested spice group years ago, and one day - when I have enough child free time and money to join, I'm planning on giving that a go. At the moment it is beyond my budget.
In the mean time I keep in touch but don't chase up friends. I offer to meet up and do things, but make my own plans which they can choose to join in with or not, rather than relying on them.
MN is a great way of finding help and support and people to talk too if you feel low or unable to cope. Or just to distract yourself of an evening - there's threads here for all sorts of interests and hobbies so there may be something you find interests you too.
Hopefully you'll find that in time you'll be ready to move on and you will regain that confidence to get out there and find people who are more like you and to find clubs or groups which fit in with your life and maybe you'll start to make friends through your common interests or shared experiences that way.
I'm starting to get there now, and I'm sure you will too.