Ok I broke up with my ex about 8 weeks ago, I have been doing fine but recently I sent him a message asking him how he was he replied by saying his got another girlfriend which was a friend of mine, and that I should leave him alone? The major problem is I work with his mom! How can I cope with him being with some one else even though I ended the relationship? We were together 4 years 10 months?

I know it's difficult, I went through the same thing. I broke up with my boyfriend of two years but it still hurt to see him with his new girlfriend. My thoughts are that his new girlfriend is just a rebound since it's only been 8 weeks... But right now you should try to avoid him. It's best if you know as little as possible about his new relationship. I understand this is hard, since you work with his mom. But try it anyway. Don't text or call him, don't check his Facebook. It'll only cause you pain. Try to focus on other things, have fun with friends. 4 years is a very long time, you'll need a some time to get over it. But it will get better.

Is regretting my decision normal?

Of course its normal to regret breaking up with a pretty long term partner, and seeing them move on so fast.

That will pass as you rebuild a life that you enjoy without him in it at all. Matter of time, and having friends, family, and activities that make you happy.

Regret is normal at first. But think about why you broke up with them. Ask yourself if you'd still feel regretful if he didn't move on so fast. That really helped in my case. If you had a valid reason to break up with him, you're better off without him. You'll find someone who makes you happier.