Student loans are not considered support provided by the student. Take a look at the TurboTax article below for a view of this question from the perspective of the student trying to determine if they have supported themselves.
Without knowing the full value of the support that you did provide your sons, the question about whether you can claim them or not cannot be answered by me. However, there are some things to consider that may help you figure it out, such as the cost of the health insurance and your home costs for the times that they may have been home from school (summer).
Son #1 is more likely to qualify because he attended school for some part of at least 5 months of the year (full-time student). You would compare his earned income with the amount of support that you provided to see if you provided over half.
Son #2 may not have attended school for long enough to qualify for the earnings exception for full-time students. He would need to have been in school for a portion of at least 5 months during the year. Otherwise, his earned income is over the limit to be able to be claimed as a dependent.
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