Thank you for requesting my help.
It sounds like you have not yet dealt with the original relationship and are fearful of allowing yourself to mourn your loss. Any time a relationship ends, there is a loss to work through. Because you went from one relationship to another, you never had the time to work through your feelings of loss and now that you are alone, these feelings are there, making you feel fearful and upset. Because your loss involved a trust issue, you have not had time to work through learning to trust again.
It is very painful to face a loss. No one wants to have to feel sad, depressed or upset. As a society, we try to avoid loss and sorrow as much as possible. But when you are confronted by those feelings, it is important not to bury them. Burying them only causes you to express those feelings in other ways, possibly damaging ways.
Start by giving yourself permission to feel different feelings. Be upset, angry or sad. You lost a companion, someone to turn to and someone to trust. Betrayal is a very strong feeling. It takes time to learn to trust again. Realizing that just because you were betrayed in one relationship does not mean it will happen again is important.
Relying on friends and family to talk to and help you work through your feelings helps as well. You do not have to be alone, which is what people often feel when they lose a relationship. Being with others and using the supports you have helps you recover faster.
Express yourself as much as you can. Talk, write, paint or just yell and scream. Anything that helps you express your feelings about your relationship. It is very therapeutic and can help you heal.
Remember, this too shall pass. When you are working on your grief and trust issues, you will feel better. Move towards healing and new beginnings. Don't allow yourself to wallow and get stuck in sadness. Look forward to the day when all this is behind you.
Here are some resources to help you:
How to Survive the Loss of a Love by Peter Mc*****, ***** H. Bloomfield and Melba Colgrove
Coming Apart: Why Relationships End and How to Live Through the Ending of Yours by Daphne Rose Kingma
Rebuilding: When Your Relationship Ends, 3rd Edition (Rebuilding Books; For Divorce and Beyond) by Bruce Fisher
You can find these books on Amazon.com or your local library may have them for you.
Let me know if I can help any further,