12 words with one word exposed can be cracked my a mid range GPU in about 6hrs.
Please go with 24.
Discussion
no, 12 words is equal to 128 bits of security, roughly speaking, 12 words is 132 bits, the rest is integrity protection
128 bits of security will take you at least 100 years to break, assuming the current rate of increase of computation capacity continues
make 24 an option though, it's beyond literal billions of years crackable, assuming you used good entropy