Story beginning from an online class

This one part of a story that I am writing for an online writing class. I would love to hear anythng y'all care to say about this. Critique please. The next post will be the second part.

Catherine drained the amber liquid from the glass, listening to the ice clang back to the bottom. She enjoyed the bite of her drink, knowing that the numbing effect she craved would soon follow. As she filled the tumbler again, she replayed the incident this afternoon that was driving her to renew her friendship with her once constant companion, Jack Daniels.
She hadn’t noticed the man when he entered the store. The door chimes that had so annoyed her when she started working at the Stop-n-Shop five years ago were now nothing but background noise. She was engrossed in her book with the Fabio inspired cover art, so she didn’t bother with the customers until they made their way to her counter.
He made his presence known by barking at her to put that trash down and get to the counter. Ordering Catherine Angela Harris to do anything was a big mistake. She doesn’t take orders well, not even when they come from the man who signs her paycheck, but the man’s main mistake was addressing her with that one word that will raise the hackles on any woman. Catherine’s two ex-husbands never got away with that kind of disrespect and there was no way some redneck in a convenience store was going to get away with it. She didn’t care what Mahir would say later about how she treated the customer, she was going to tell this little creep off. She jumped off the stool, sending Fabio crashing to the floor and turned to face the man. She started toward the counter when she saw the man’s hand, and what he had in it. It was nickel-plated and cocked.
She froze, not daring to look at his face, afraid that if she did, he would have no choice but to eliminate a witness.
“Give me the f*#@ money now!” He ordered.
Her hands shaking with fear, she opened the register and drained the contents into a small paper bag. She grimaced when she realized that it wasn’t all that much. She had just come on shift, and she hadn’t had many customers yet. Her fear intensified, worried that the robber would take out his frustration with the small amount of cash on her.
“Now, give me the poker machine money!” He demanded.
Still fearful, she felt a little better, knowing that the poker bag held two thousand dollars. Surely, he would be satisfied with that haul and not hurt her. She also was glad he had asked for the poker bag, because now she could call for help without him knowing. The panic button had been placed right next to the lock for the drawer where the poker machine money was, so that they could push it with less of a chance of a robber catching them alerting the police. Catherine fumbled with the keys, dropping them once, before getting the key in the lock. She was just about to push the panic button, when the man spoke.
“Hurry up; this ain’t getting the baby no shoes!”
Catherine stopped. She knew that stupid saying. She hadn’t heard it in over twenty years, but it was as clear to her as when Robert, her first husband, had said it every time she was running late. She had come to hate that phrase, almost as much as she hated Robert. Robert, the man that had taken her boys away from her, and kept them away from her all their lives, simply because she had a shot or two of Jack Daniels every now and then. She had to look at the man now. There was no way this could be Robert, but she had to be certain. She pretended to fumble with the lock again, while she looked directly at the man. It wasn’t Robert. This man was in his thirties; Robert would have been in his fifties. As she was about to finish getting the money and push the alarm, she met his eyes. She stopped again. She knew those eyes; they were Robert’s eyes, but this wasn’t Robert.
“No, this can’t be. It can’t be.” Catherine screamed at herself in her mind. She looked at his face again. It was pock marked and showed a life committed to alcohol and drugs, but she knew the face and her heart broke.
“What are you doing down there? Hurry up or you will be sorry!” The now familiar man bellowed.
“What am I going to do?” She agonized. She abandoned the panic button; she could not bring the police here, not yet. Quickly, she got the poker money bag and placed it inside the other bag. As she gave him the money this time, she looked directly at him, hopping that she was wrong. Even as he backhanded her, telling her that she shouldn’t look at him if she wanted to live, she knew she was right and shame now replaced the fear she had been feeling. She had fallen to one knee from the slap and he told her as he was leaving that she better stay down, and not call the cops or he would come back and kill her. Then he was gone.
She burst into tears, not from fear or pain, but from shame and loss. She sobbed for a few minutes, but she knew she had some things to do, so she wiped her face clean and got started. Before she pushed the panic button, she went into the office, thankful that she had been promoted to assistant manager; otherwise she would not have been able to pull the tape in the surveillance camera. She took the tape and put it in the suitcase she called a purse. The cops wouldn’t look in there, so she would be ok. She pushed the button and waited, glad that the robber had not actually touched anything at the counter except the money bag. The rest of the day was a blur. After the cops left, Mahir sent her home.
Now, as she drained the glass again, she wiped the tears away from her face. She put the glass on the table and picked up a photograph. It was a snapshot that Beth, her youngest daughter, had given her a year ago. It showed two men in their thirties, obviously brothers. As the numbing effect that she had been longing for washed over her, the picture slipped from her hand and drifted to the floor.
“Robbie Jr, I am so sorry,” she slurred as the man from the store stared back at her from the photo on the floor.