Happened to me last year with a very late hard freeze. Fortunately I had plenty of replacements.

I'd leave the least damaged ones as they will come back, tho not as healthy nor as productive. But I would also pick up some back-up seedlings while the selection is still good.

Sorry for your losses.

Dave

I lost a bunch one night (about a third) because I had them in my mini-greenhouse and was too darned lazy to bring them in. They mostly looked like cooked spinach the next day. I kicked myself roundly. Several made it. I sent them off to my dad's real greenhouse, albeit unheated. Another hard freeze and they were toast. I have about 3 survivors from the beginning and they look nasty. Luckily I started a bunch more seed and they look great. I got off to a late start last year, as the seed order was a bit late in arriving. Still by the end of summer they were monsters and I was getting ripe fruit from them. So I am not too worried about starting over late this year because I know they can still do it.
I was told once that a seedling that experiences stress can come back even stronger for it. I just don't know about THIS kind of stress.

The two responses to my post show the two points of view about badly stressed tomatoes, viz., stress makes 'em tougher; stress sets them back and reduces production.

So which is it? There must be some empirical evidence. Anxious to hear more!

RB

Last season I snapped off a large sucker from a Beefmaster plant that I had missed earlier. I just jammed it into the ground about 4" deep and watered it with some fish/seaweed emulsion. In two days it was completely wilted and laying on the ground. In a week it had perked up and was again standing upright and growing. It produced some of the largest and nicely formed tomatoes I harvested that season. Now, that's stress. It never even got early blight. Tough plants (weeds).

Different types and levels of stress produce different results. Note that triple_b agrees above that THIS kind of stress (freezing stress) may not apply to coming back stronger.

A broken off plant is still intact at the cellular level in the stem. The inter-stem tissue still "works". If it can survive until it re-roots above the break the stem cells will work fine.

A plant that is stressed by transplanting can benefit from the stress by changing its root structure.

A plant that is frozen suffers cellular rupture from the ice crystals and stem tissue damage. How much depends on how badly it got frozen. Those cells and that tissue will not recover or regenerate and so will affect any future growth and production of the plant.

Hope this helps. ;)

Dave