I incured 40K of loans to get a new degree to get a better job, now ex wants to pay less support, but the increase won't cover my loans payment

Your new salary is used in the calculation of two components in a divorce, ie, child support and spousal support. Your question is not specific on what it is your H is trying to use your new income to achieve and the answer may vary based thereon. Child support is calculated by using your combined net monthly income and applying the statutory formula. For child support, your current income is used regardless of how you have risen to the current level of income or the debt attached to that rise. The loans incurred for your education, although in your name alone, may be considered marital debt if incurred during the marriage. The argument is that your H ought not be able to benefit from the reduction he will have to pay in child support by virtue of your increased income and at the same time, saddle you with all the debt you incurred to better your income. The same argument can be made if he is now seeking alimony from you or is arguing that your alimony should be lower due to your lower "need" due to your increased income.