Thank you for writing in here.
I'm sorry to hear you.
It sounds like your girlfriend (your ex)of 5 years has been dishonest with you sometimes.
I can imagine how anxious you must have felt about her behavior.
Perhaps, your anxiety
about her had to do with her dishonest behavior.
Possibly, she may have narcissistic or histrionic personality disorder
as she may lie at times, be attention seeking, and dramatic in her behavior.
Unfortunately, you may have been trapped in always checking her activity as you knew she has been doing something behind your back.
You may have been obsessed with her as you are in love with her and you are constantly anxious about her behavior, action and motive.
She may not give you trust, peace and emotional stability as she may have emotional issues with people in general. Perhaps, she may be narcissistic as she feels she can be dishonest with you and doesn't want you to leave her unless she has another person to "focus" her.
I would advise you to start seeing a psychotherapist weekly for a few months to deal with your relationship with her and current big feelings. I can imagine how hurtful her behavior has been to you as you wanted to trust her and her words.
You may need to express and process all your feelings and thoughts about her with a counselor in order for you to move on from this relationship.
I hope you overcome this with available help.
Please let me know if you have more questions or I have overlooked any. Warm regards,