I obsess over people (one person at a time) and constantly want to be in contact with them and change myself do be just like them. I don't want to be with anyone else & can't focus on anything. Help?

That sounds like it would be very difficult and frustrating. Torn between wanting this person and to be like them but not being able to focus on anything else must be tormenting at times. I wonder if there is anything in common with the people you become attached to? Some people who have not had emotional support become attatched to someone that shows them the care they have always wanted or for others it may be a low self esteem issue and they idolize this person. Finding what the underlying reason may be and having some focus on that can help you to understand your attachments. Perhaps speaking with a trained professional may help in uncovering this and help you break free

You need to learn to be your own person independently from others. It is not always easy to do it by yourself so you might want to seek help.

It sounds like you're uncomfortable being all by yourself, facing only your self? If you've defined yourself only by how you are with other people, you're doing yourself a disservice. You can be your own best friend, it sounds corny but it's true. It takes time, and it can be scary to cut ties and stop thinking about another person day and night. You may feel out of control. But you do have control, control over your own self and your own life. If that's too scary, just keep talking, keep asking questions, and find the answers that your own self will provide. Advice is fine, but ultimately advice is there to lead you right back to yourself. Obsessing about anything is unhealthy, even yourself. I hope you can find a healthy balance of attachment to yourself and others.