I'm on the job, and I'm having a hard time on it cause this girl that works on the job, she was the one that was messing around with my boyfriend at the time, and when I found out what they were doing it was around the same time my brother died.

Anyway the girl starts working up there I try to talk to my manager to see if we can work different days. And when the manager work it around like that, she want to come on the job. Now when I go into work she is just standing around. Then when I talk to my manager, and get that to stop. Now she calling on my phone, and I don't know how she got my number, or what she told the manager, but now she has it looking like I'm trying to cause a problem with her, for no reason, when she know she was fooling around with the guy I was involved with.

Now I have left her alone, and I didn't put her down, or went around talking about her, but she seems like she can't do the same. She is making it hard for me to the point I feel like maybe its best if I quit.

What do you think I should do?

Well first of all dump your so called boyfriend!!
I have no idea what your still doing with him.

As for the girl that you are working with don't quit because of her jobs are hard to find these days

Just go about your day work hard and try to ignore her
At least you only have to put up with her for 8 hours a day which is nothing
Try living with someone and working with them while they are sleeping with your room mate and they are claiming to be your girlfriend all the while. Then when you find out they do everything they can to rub it in your face and yet you still stay on for a year! After the fact.

Now that! My little on Is a hard time
Your lucky you get to go home at the end of the day and forget.

So your situation is so not bad enough that you should quit
But what you should do is get rid of your boyfriend

The problem is the boyfriend, because without him allowing her to get on your case by fooling around with her, then she has no reason to screw with you. She WANTS you to quit, and leave this fellows life because you are her competition.

Let her have the cheater, all to herself, and he will surely cheat on her, as he did you.

Then you will have a job, without this cheater, or his whore, and she will have the cheater, and some other whore.

Poetic Justice.