First off, I’m sorry for your pain
Now, for my take (I’m writing from “the other side”, prolly around your mom’s age, maybe older).
Any lasting relationship must, absolutely must be built on friendship, mutual trust, respect and communication. Starting off with sex is the *worst* way to begin. I may be terribly old-fashioned about this but there has to be something that will keep you together once the sex wears off (I’ve been married over 11 years and he and I were together for five years before we married). Sex should come later, especially once you’ve been through some hard times where you find yourself questioning whether or not you really care for this person.
The initial breakups were prolly because she didn’t know what she wanted. She wanted someone around when she needed cheering up and when she felt good about herself she wanted her independence. That’s not unusual—guys do it, too. I think you may have had different expectations on where you thought this relationship was going. There are so many definitions for the word “love” and without an understanding of the context it’s very easy to pin your hopes to something that may or may not be there.
You mentioned there was an underlying tension. Did you ever take the risk and talk about it? This may have helped a great deal. (Lesson to learn: no pain, no gain).
It’s hard to give someone space when you care for them a great deal because there’s always a chance that s/he may decide that independence is the better way to go. I personally don’t think that a month was enough—my first “True Love” and I were together for just over four years (and were planning to marry) and it took me several months (at least six) to get over him. Depending on how long she was married she may have needed more time. I’m not implying that you put a time limit on her, she may have decided that a month would be enough.
It’s not unusual for someone to think of an “ex” fondly and discover that a break was the wrong thing to do. However, based on the reasons for the breakup you provided she may be on a toxic merry-go-round and, hard as it may feel, you may be better off without her.
OK, so what to do:
1. No more contact with her, even if she calls you just to see how you are. It’s waaay too easy to fall back. Avoid contact with any mutual friends for awhile. If you have to be around them and they mention her change the subject. They may feel they’re doing you a favor but they’re not.
2. I don’t know how old you are but you must get out of the house and be around people. Even if it means just going to the mall and walking around, leave your misery behind you.
3. Time to rid yourself of anything that reminds you of her. Any pictures, keepsakes, whatever. Clean the house. Rearrange the furniture. This may help you get a better sense of yourself and wipe out part of the memory. Cleaning the house is no fun but it’s a way to spend time.
4. Is there something you’ve always wanted to do but never did? Now’s the time. Join a club, volunteer time, whatever. Develop a new interest. You’ll meet people who share that interest and you’ll have something in common with them. If you have a friend you can talk into going with you get that friend to be your “personal trainer” to make you go to whatever event you’re supposed to go to. Keep you true to yourself.
5. Develop your sense of self—define yourself in terms of yourself and not in terms of other people. Who are you really? What do you believe in? What are the most important things to you?
6. Where is your support network? They can help a great deal. They did for me, believe me.
7. Go ahead and mourn your loss. That’s expected. You will get better over time but you have to help yourself. Your feelings are still raw but if you can take that first step you’ll be on your way to healing. The first step is always the hardest (I speak from vast years of experience) but once you do you’ll be glad.
Good luck and please keep posting.