Hi, Jennifer!
I know what you mean that trying to share diet struggles with someone that only has 20 lbs to lose can be disheartening. I'm glad that you have a good support network, though, because good friends (no matter their size) can be lifesavers when trying to keep your sanity on a diet.
I have high blood pressure as well, although I've had it since I was a much much lower weight (below 200). I have to take meds that I may have to take the rest of my life. I also take thyroid meds that I may have to take the rest of my life. I hate the idea of taking pills, so it is really depressing to think I have to be dependent on perscriptions to keep my body going.
Given your heart condition, I would recommend that you meet with your doctor before you start a new diet plan. He may, for example, not want for you to cut your calories too low or he may recommend the sort of exercise that would be appropriate.
I've just recently (maybe 3 weeks ago?) started the DietToGo program where they mail you all the food you eat for the week. I've lost a few pounds, as you can see in the ticker, but of course I have a LOOOOONG way to go. For exercise, I LOVE my treadmill. It's not so much that I love the act of exercising so much, as I love the fact that I let myself watch any trashy TV show I want while on the treadmill.

For instance, I love watching Americas Next Topm Model

but I would never watch that if I wasn't on the treadmill to justify the total waste of time. LOL! So finding an exercise that you actually enjoy will be great. Now that winter is setting in (I live near you in Wisconsin) finding and indoor activity would be best.
I'm so sorry that you had to go through such a medical scare. But the positive thing that has come out of it is your committment to yourself. These boards are fun to read and be motivated by... so I hope you stick around.
Take care!