In his 22 years as a high school guidance counselor, Bernard Shulman never felt anything as emotionally painful. It was his job to tell 12 seniors at North Shore high school, Glen Head, N.Y., that the Social Security benefits they planned to use for college tuition had been cut.

As dependents no longer eligible for Social Security student benefits, the seniors are from widowed families who are now feeling the full impact of the Omnibus Reconciliation Act passed by Congress last August.

Nationally, at least 40,000 high school seniors with one or both parents deceased have lost their benefits. In addition, 734,000 college students from widowed families currently receiving money will see it cut back--by 55 percent in 1982 and in smaller portions the next two years, until 1985 when the program is scheduled to end for everyone.

Bernard Shulman's pain was being, in effect, the system's hit man. It was he--not President Reagan advancing his economic policies, not the members of Congress who voted for the cut, not the Social Security officials who are carrying out the law-- who told the seniors that no money is left.

"What bothered me," Shulman says, "was telling the kids and seeing the expressions of helplessness, hopelessness and anger, as they realize they were caught in this. . . . Some cases are especially sad, like kids with both parents dead, who planned to use their Social Security checks to continue their education as well as feed and clothe themselves."

Shulman, along with guidance counselors in school districts nationwide, began spreading the bleak news as soon as they learned it, which was only recently. This particular cutback received little publicity, even though with an average benefit of $259 a month the loss to each student could be devastating.

What particularly galled Shulman was that official notification of the cuts won't be sent by the Social Security Administration to the individual students until sometime in the spring.

Students notified directly could arrange to graduate in January and be in a post-secondary school, thereby being enrolled before the May 1, 1982 eligibility cut-off date.

In Congress, Rep. Thomas J. Downey (D- N.Y.), who opposed the cut as unfair when first proposed by the Reagan administration, is now trying to alert others in Congress to get this word to the high school seniors. He has been explaining the dirty trick being played on the students. To be in college on May 1, they must enroll now. It is already late. Downey, not long out of college himself, says that "I have found the guidance counselors willing to work very hard to help these students."

At North Shore high school, Shulman said that of his 12 Social Security seniors, who are five percent of the class, nine have chosen to leave school early to go to local colleges. Administrators at the colleges, with more sympathy for the young than the Reagan administration, are cooperating.

An official at the Social Security Administration says that his agency shouldn't be taking the heat from either the guidance counselors or congressmen like Downey. "We administer the law as Congress passed it," he says. "It's not the intent of this agency to send out a notice saying Congress passed this law but if you choose to get around this, do such and such."

Perhaps that can be defended legalistically. But if the government is meant to be serving the citizens, a conscientious agency would move quickly to tell those citizens of changes in the law that affect their lives. For Toby Ann Meisel, a widow with one college and one high school child and who is Rep. Downey's legislative specialist on Social Security, "it is clear why the students aren't being told. The Reagan administration doesn't want them to know because the students would be spending money that otherwise won't be spent."

The debate about the cuts is long over. That the administration sought to save money at the expense of widows and their children was in keeping with its policy of hit-the-weakest-the-hardest. It is an extra insensitivity not to be candid and helpful after the hitting is done.

There is a consolation. Should these 40,000 high school seniors, as well as the 734,000 students now in college, be asked to write a final term paper on American Politics in Action, they could merely tell about their own victimization and probably earn an A-plus.