Sorry to hear that. It is not easy, I know and time heals wounds rather slowly. Maybe you can try to be calm and asses is it really over and how do you wish things will go from this point on.

i have the urge to text him or call him. but i know its no use he wont change his mind. its so painful i feel like i cant breathe at times.

Sorry how you're suffering. Please see a therapist who will help you. Don't keep to yourself. You can get through this and do much better with help. Connect with me as a friend if you like. I'm seeing a therapist who is helping.

A break up is certainly one of the most difficult, bone crushing feelings a human can go through.
There are three things I BEG you to keep in the front of your mind.
1. The horrible feelings are temporary and they will get much better in time.
2. The best way to help yourself is to help someone else. It will make you feel better right now even if it’s just a little bit better. Help anyone with anything.
3. What every you pay attention to grows. As difficult as it may seem do, pay attention to only positive things. You only have 100% of emotional storage. If you fill up 80% of it up with positivity then there is only 20% available for negativity. The same is true if you flip them around so stay on the positive side and there will be little room for the negative.

All easier said than done but at least you have a few things you can do to move in the right direction.

You will feel better and I truly hope it starts right away.

Rich

You got some good advice here, so I'm just going to add that what you're going through right is a horrible feeling. It sucks. But it's just a feeling. Let it pass.
Calling him is just giving him the power to hurt you again.

You need to do whats counterintuitive right now and LET HIM GO.

You will be OK !

I agree with all the great advice everyone has given. Please remember the feelings are normal. You will feel crazy bc of all of the feelings--- but guess what you are not-- You are human and its gonna hurt but know that one day you will wake up (although probably hard to think of right now) and feel better. Its an awful feeling, but just like mentioned before, they are just feeling-- they will go away. I promise. I know I'm a stranger, but just believe. Keep writing on here. you will find so much support and insight. Keep in touch.

You can use this opportunity to examine those feelings.

What lies have you told yourself that you're feeling this way?

That you can't live without out this person?

Sure you can.

That your life is over?

No it's not

That you'll never be happy again?

Only if you stubbornly refuse to get on with your life because the saying when one door closes and a million more open is true.

Don't allow those negative thoughts to abuse you.

Amazingly great replies here. My initial reaction to my wife leaving was similar. Breathing was difficult, food was of no interest and my entire muscular system felt like it was tightening and shaking in odd ways. I knew it was all temporary and little by little it did get better. It's all temporary! Remember all of this only gives your ex power and none of us want that-it's no good for us or our recovery.
Utilize a therapist if needed or at least lean on good friends/family to get you through any time you need to vent. Get out, indulge yourself a little, find the positives and set goals for moving forward. I love the post about helping others actually helps you in times like this. Keep coming back to these boards too for advice-there are some great people here. You will get through this!!!

What a fantastic bunch of replies! Reading them literally added a significant amount of motivation to the part of me that wants to help others.

Thank you all and pixiedust, I hope you found something here helpful as well.

It is very comforting knowing you are not alone in a difficult situation and this clearly demonstrates that you are not alone. It always shows you that many people know EXACTLY how you feel, have been EXACTLY where you are and have GOTTEN through it as you will.

Best,
Rich