I'm in a similar boat: I took my eye off the 'staying healthy' ball, and now I've got all kinds of worries. The only plus point is, like you, I was doing well with my diabetes control at one point, and I guess I can do it again (and you too!). I made a start about a month ago after a shock at the doctors, and got a little weight off. I've had a bit of a lapse of late, but I'm still ahead of where I was a month ago.
My plan is to keep it simple: I like low-carb food and coffee, so I'm going to try to keep as low-carb as I can. My big vices are crisps, bread and alcohol, so I'm trying to really keep well away from that sort of stuff. My main goal is to get my liver emptied of stored glucose and get my weight down by about 30lbs.
I guess my advice would be to try to condense your concerns into a main 'do' and a main 'don't', and then have some sort of achievable goal in mind- something specific and measurable. I'm no-one's example to follow, but I think the plan I'm going for should more or less work. Good luck with it!