Since I'm just a little over 10 pounds more than you at about the same height, I can say that no, we're probably not too heavy to start jogging. Especially not if we take it slow. But for me also, the cardiovascular work out of jogging doesn't even begin to compare to what seems like a decent intensity workout from something like biking or seated ellipticals etc. I am also super winded and I feel like I'm constantly fighting to breathe properly. I've only done 2 days of 60-second jogging intervals so far. I think that training my lungs how to work properly is probably going to be one of the best results from learning how to jog, as that will be a skill that will be more helpful for any future activities.
Just take it slowly! Do what you can, as much as you can, without pushing yourself to the point that you hate it and will quit. Slow progress is still progress. And jogging should help us lose weight, and I'm betting that as the weight does come off even more (in addition to all the cardiovascular system improvements from the workouts) that the jogging will just get easier and easier.
Since we're at about the same starting point, would you like to be learning-how-to-jog buddies and see if we can help each other get in motion and stay motivated?