It hurts every time I see my ex with a new girlfriend.
How can I let him go?

Where are you that you see him with the new girl? Unless there is a child between you I'd get away from him, even if that means you have to take the initiative and leave where he is at.

I'm just 15 and there's no child. =O
I see him while I am hanging out because we live near each other.

Until you're well along with YOUR next relationship, you have nothing to fend off the sadness.

The feelings you had will always be there in some manner or another, the only cure is stronger CURRENT feelings/relationship for/with someone else. Until then, it's just a wait.

Welcome to the next chapter in your life. That's when you notice boys, date them, sometimes they will break up with you, and sometimes you will break up with them. One of these days, you will be the 'other girl' too, so don't be too sad over it and don't blame her. It's all part of growing up and it happens to us all.

As JB said, time will heal, and so will a new friend.

Keep busy with your female friends and activities and enjoy your yourth. It won't do you any good at all to be upset every time something like this happens, as it will not be the last time. Things like this will actually help you learn how to cope with rejection, make better choices in the future and not let anyone break your self-respect. And, don't always believe what your 'girlfriends' suggest, as they are just as confused as you are at that age.

We are here for you any time you need to talk, so stay with us and we will help you through the rough parts of this new chapter in your life.

Within each of us there is the child, the teen and the adult. We just have to learn which one to let take control in given situations and that takes practice. We are all human so that means we are not automatically born with all this knowledge. Not even a baby walks after it's born... and life teaches us more and more each day.

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A few suggestions to think about: try and respect others as you would want to be respected, don't let anyone pressure you into something you are not ready for, and when in doubt about something - there is always someone out there to talk with - even if it's your mom (she was once your age, honest) and this site. Take care dear.

That's natural dear. Everybody goes through it, you're not alone and the first ever.This shall pass. Is there any possibility for you to live somewhere else away for now?