Summarize this article:

After you’ve been replaced or rejected, you may start to feel negatively about yourself. You may start to believe you’re not worthy of relationships, but you are. Learning to accept yourself again may take some time and may be challenging, but you can do it.  Give yourself a break for any mistakes you’ve made. Everyone makes mistakes, and you can learn and move on from them. This knowledge can enrich your future relationships. Avoid calling yourself names. That’s not going to help you move forward. Even though you’ve been replaced or rejected, you will be okay with time. Remember that now you have more time to focus on yourself and find better relationships. Your ex might have moved on quickly, but this just shows they're not capable of being alone. Prove to yourself that you're capable of being alone by:  Focusing on your unique abilities and qualities. Starting a new hobby. Participating in sports or other active pursuits. Focusing on your education or your job. To help heal from your sense of being replaced, spend time with other people. Reconnecting with others and trying to find somewhere else where you belong will help you get over the loss of your other friends. If you’re not sure where to meet new people, you can try:  Volunteering. Joining a sports team. Talking to someone new at work or at school. Joining a gym. Being replaced or rejected never feels good. But it’s important to remember this is a normal part of life. Not everyone you meet is going to like you and you’re not going to like everyone you meet, either. Sometimes relationships have to end. By accepting this, you can focus your energy on yourself and creating better relationships.

Summary:
Accept yourself. Stay positive. Meet new people. Accept that exclusion is a part of life.