This is a very common issue, even Mark Allen had to slow way down and walk. I have walked a ton myself. But if you stick with it, ask questions, read the heart rate forum and search it for our posts on this matter. (you will have access to the heart rate forum with a paid plan) Then you will find tips, tricks and many things that can also help you get aerobically fit.
As to weather 132 is the right number, the web site will help you calculate it very accurately.
Finally, I know its discouraging but I personally rather be a little dicouradged in training than in racing and if this is the path that will help me race better and faster then I think its worth it. But it takes a team, you and us to make it happen.
We look forward to help you once you get your plan going.