My wife says she doesn't love me anymore.

A year ago my wife told me she'd kissed one of her work colleague friends. I forgave her but last week she told me that, she doesn't love me anymore and has no feelings if love for me at all.
So it's not just not sure !!

I'm devastated and have nobody and nothing to live for without her.

She won't talk about it and is just carrying on completely normally. I'm exoecyed to do the same.

All I can think about is killing myself so she can find someone she is happy with, but I'm so pathetic I can't even do that.

What can I do if she doesn't live me all all and I need her.

Ask her when she stopped loving you, and if she wants a divorce if she has cheated she should get no spousal support and then you both go separate ways and try to start new lives.
You can't make someone love you especially after they told you they no longer love you, and don't kill yourself..firstly she won't feel guilty and you one day could indeed find your great love and be happier than ever was with her.

Leave your wife, get a divorce, go to therapy and find a support group. That should help you slowly recover.