That's rough man.
The best thing to do is regroup, and get out as quickly, and painlessly (emotionally and financially) as possible.
Most guys appreciate the value of doing approaches for "practice" but few people realize the value of "nexting" for "practice."
This is an unfortunate example of someone who (apparently) had no trouble getting into a relationship, but not sure how to get out. No exit strategy, as it were.
To the OP, if you realize your mistakes, and take a step back and learn from them , and use them as points to improve yourself, you won't likely repeat them.
Even if you are in a happy relationship, you've got to remind her that you have no problem walking at any time.
This can be done many ways. For example if you are out together, say at the mall, and she happens to wander into a purse store, don't follow her. Keep on walking and force her to find you. Let her know you won't follow her. She must follow you. No lectures, only behavior.
Also, make it a point to find any excuse to talk to attractive women in front of her. Salespeople, clerks, cashiers, etc.
Let her know, through your normal behavior, that you have no problem walking, and no problem striking up conversations with females.
Let her imagination do the rest.
Done correctly, when some goof at work tries to talk to her, instead of thinking "Wow! Attention!" she'll think "Sh*t, I'd better be careful, I could lose my boyfriend/husband over this."
The danger of you disappearing and finding somebody you judge to be better than her has always got to be in the forefront of her mind.
Hang in there OP, you'll be fine. You've got the right attitude.