Split skin on tomatoes as they ripen is not all that uncommon, but it is quite easily avoided with regular watering…
Moving from dry to waterlogged soil will cause the tomato skins to split when the fruits start to ripen, so try to keep the soil consistently moist and this should right itself as the next fruits come through. It is also worth using a fortnightly liquid feed once fruits start to form.
Be careful to harvest your tomatoes as soon as they are ripe – if left on the plant they will over-ripen, and at this point splitting is much more likely.
If your tomatoes are split, you may prefer not to use them raw in salads, but they are great for cooking down into pasta sauces etc, so don’t chuck them out!