@Retreater -- I can empathize with your competing desires both to ease up on the amount of work you are doing and also not to disappoint or blindside the people you are running for. I see a lot of posts in this thread that are very assertive in saying what you should do and many of them suggest being pretty ruthless and endangering relationships you have, which might be fine, but in general people game with friends, and it can be a bad thing to harm those relationships.
Sometime that is necessary, but none of us know you and your relationships as well as you do, so I think it's a bit dangerous to make dogmatic statements about what you should do, so instead I'm just going to suggest an approach that works for me.
When I get stressed with too much stuff and too many expectations, I like to make a list of all the stuff I do, add some info to each of them like "how much time does it take up?", "how much enjoyment do I get from it?", "how much I enjoyment do I give to others by doing this?". Then I order them using my gut feeling
I then like to make a cut at what I would do in a perfect world; everything above is stuff I'd generally like to be doing and everything below stuff I'd generally prefer to drop.
Now it's easy for people to say "and now stop doing the the things below the line" but life doesn't work that way. There's people you like who you don't want to piss off and other considerations that get in the way of simple clean solutions.
For me, what I do is try and move in the right direction. for things below the line. I might look at plot arcs and plan to finish up the campaign with a fun, well-planned and hopefully memorable end, so that people don't feel you're quitting because you hate playing with them (even if that might be a bit true). Or I'll switch to a game being monthly. Or from being self-plotted to using more modules (I quite liked 4E Gardmore Abbey, btw).
Even for things you generally enjoy, lightening up the workload is a good thing. Frequency of gaming can be reduced. Can you find ways of reducing travel time?
Another option -- one I've used a few times, is to take an extended break (2-3 months is good) to give yourself time both to relax a bit and to plan out the next arc. Say something like "I'd like to take some time to do some long-term prep for our campaign; we've done a lot in the last year and I want to make sure I get a handle on it and am ready to run the next set of stories, so I'd like to go on pause until mid-July. If there's any storyline or idea you'd like me to focus on, please let me know".
If I had to give one piece of advice, it would be just to do
something for each campaign you are running to move it to the state you'd like to be in. Reduce frequency, run canned modules, plan an exciting end, reduce travel time, switch to a simpler system -- whatever you think will help you. But take steps to move towards feeling better about running. It'll still probably feel like work for a while, and you may have to make hard decisions involving friendships and energy, but it feels like you're driving 90 on the highway, and rather than slamming on the brakes, maybe just ease down to 60 for a bit and see how that goes.