Welcome, brother.
What we need to sort out first is your drinking. No lager. Repeat. No lager. A decent red wine or spirit of your choice is perfectly acceptable. Leave off the pints. I can't stress that enough. The beer belly must go.
Every morning start easy exercise. One push up. One curl. Next day move it forward. Very quickly you will find yourself becoming the buff sex object you always knew you were.
Then, when you meet your ex, you are a new person. Strong. Confident. In control. Then ye rape her. The **** that she is.