I have core shorts. I also have a Desoto T1 vest.

If you put both of these on.....you'd be warmER.....and probably keep up with the faster lane.

And I'm jealous of your pool temp. I'm floundering in one that's 85+ right now. It sucks.

So, do I stick with the great masters group and deal with the hypothermia (ok, not really considering that. I'm going to impair my immune system and get sick if I keep that up), switch pools for now and swim alone, or show up in a wetsuit a smiling idiot knowing I'm the joke I am (with or without the wetsuit)?

Saw you work in topology; riding partner is C. Reidys

First of all people comparing their surfing/ocean swimming is way off base. 68 degree fresh water is waaaay colder than 68 degree ocean water, so there is that.

First of all people comparing their surfing/ocean swimming is way off base. 68 degree fresh water is waaaay colder than 68 degree ocean water, so there is that.

Most likely you are swimming in a salt water pool? If so just swim in your wetsuit, the water in those is virtually drinkable, it is not going to hurt your suit. And even if it is not, still swim in the suit, just move to the 1;10 lane and find your spot there with your new speed, perhaps you will have to even lead it.
Just rinse the suit out good each time, they are not that fragile. But you seem to be intolerant to cold water so take this time to get acquainted with your wetsuit, people don't swim enough in them..

Moved to a new place and swimming with a good masters group, quite possibly the best masters team I've ever swum with. The workouts are just great, so far a minimum of 5,000y. One complaint: they have a 1:10 base lane and then a 1:20. I'm a bit in the middle, only getting 2-4sec rest during the pre-main set feels tough. And when I've led the slower lane, I can sense folks wondering why I'm pulling the lane too hard... and at least once I've ended up the only one in the lane as everyone bailed 3/4 through the set, but that could be coincidence. The longer stuff works a bit better in the faster lane in terms of making the send offs, but the next fastest guys in the lane are finishing 5-10sec faster, so I'm definitely not qualified to be swimming in this lane.
Regardless, it's good for me and to be swimming 5:35 500y repeats on the 6min and staying completely aerobic and in control and having fun tossing in some surges to try to bridge the every-growing gaps, all which is really good for me.
Problem is that the pool temp was 70 on Monday, 68 last night. My hands are going numb, turning blue, white and purple, my legs are cramping in the cold and I feel disoriented and cognition is impaired, and though I'm bringing a fleece for the post swim walk to the trolley, I spend the rest of the evening shivering on and off. Heater will be fixed in 3-4 weeks time.
So, do I stick with the great masters group and deal with the hypothermia (ok, not really considering that. I'm going to impair my immune system and get sick if I keep that up), switch pools for now and swim alone, or show up in a wetsuit a smiling idiot knowing I'm the joke I am (with or without the wetsuit)?
I don't own a swim skin, but that can be resolved if folks think they retain body heat enough to withstand 68 degree water, noting that I'm skin and bones and get cold very easily.

Monty - What would you say is the differential between salt water and fresh water, i.e. if I can swim comfortably in 75* fresh water, would 70* salt water feel about the same??? //

It will of course vary from person to person depending on their actual perception of cold and hot water, but for me it is just about 10 degrees difference. Just sit down and think about it for a minute. When you get into a 70 degree ocean what does it feel like? To me it is very pleasant and feels like I could be out there all day. Now how about an 80 degree pool? It is actually in a lot of cases on the chilly side, most pools are around 82. I always felt like that 82 pool felt exactly like a 72 degree ocean. So plus or minus a degree from that I would imagine, depending on the concentration of salt in the ocean you are swimming in.

Chlorine and Neoprene do not play well together for very long. I wouldn't recommend wearing an expensive (not a throwaway) wetsuit in a pool for more than a couple of short swims, and even then it should be either soaked in freshwater or taken out for a swim in OW soon after.