If the new people own 25% of the company, then the previous owners own 75%. That means that the new people should get one-third as many shares as previously existed (which you did correctly). But it also means that they should have to put up one-third as much money as the company was worth previously; that is, 133M, rather than the 100M you had them pay.
Your loss is your cut of the 33M loss that your company took by getting underpaid.
If the new people own 25% of the company, then the previous owners own 75%. That means that the new people should get one-third as many shares as previously existed (which you did correctly). But it also means that they should have to put up one-third as much money as the company was worth previously; that is, 133M, rather than the 100M you had them pay.
Your loss is your cut of the 33M loss that your company took by getting underpaid.