Lily Evens knew that one day she would regret it. She was losing her best friend. But her pride was always getting the better of her.
When Severus had called her a mudblood, she didn't know what she was to feel. Shock, hurt, anger and many other unidentified feeling rushed through her all at once.
When Lily had thrown that insult at him and called him Snivellus, she had been out of her mind with rage. Once she had calmed down, she had begun to feel ashamed. That is, until she thought about what he had called her.
As the weeks went by, Severus was persistent with his apologies. He even went as far as to sleep outside of the Gryffindor common room. Lily was tempted to accept his apology and forgive him, but she could never bring herself to.
As the summer went by, she found that ignoring him was one of the hardest things she ever had to do. When the school year started up again, it became much easier with all the distractions. As the time went by, Lily found herself growing closer to James Potter. Severus was pushed out of her thoughts, but he was always in the back of her mind.
When she became Head Girl, her first thought was to run to Severus. A pang of sadness hit her as she remembered that they no longer spoke.
When she got engaged to James, she wanted nothing more to speak with Severus.
On her wedding day, she felt as though something was missing. She knew that it was meant to be Severus up here by her side in the place of her best friend.
When her son was born, she wanted Severus to meet Harry.
Lily missed her best friend. She wanted him to be in her life. But it was too late for that and now he was out of her life forever. When she had the chance to keep him as a friend, she threw it away. She gave him up for her pride.