It's a wonder that no one thought of this before. There are, after all, more ex-spouses than there are Irish, and the Irish have had a day of their own, and even a parade, for years.

But a parade of men and women waving divorce decrees in time to bleating tubas was not what The Rev. Roger Coleman of Kansas City, Mo., had in mind when he dreamed up National Ex-Spouse's Day two years ago.He did not even envision people sending each other bouquets of dead flowers, which is maybe what the name "Ex-Spouse's Day" conjures up in your mind, especially if you're an ex-spouse yourself.

Coleman had something more uplifting in mind - a day of healing.

He chose Good Friday for Ex-Spouse's Day, he says, because Good Friday symbolizes a time of darkness and fear. Sort of like divorce. And it's followed by Easter, a time of healing and hope.

As director of clergy services in Kansas City, says Coleman, he counsels a lot of people whose marriages are dissolving or who have been ex-spouses for some time. What he sees more often than not is that these people remain depressed and angry years after their divorce.

"The trauma of a broken relationship," observes Coleman, "is often a controlling force in a divorced person's life, interfering with his or her ability to form another intimate relationship." The anger that lingers on is harmful to the ex-spouses as well as their children (see related story on this page).

He admits that he's gotten a few letters from critics who think that by advocating observation of Ex-Spouse's Day he's encouraging divorce. But Coleman says he's just approving "the reality of divorce, and the options people have in the midst of it."

One thing ex-wives or ex-husbands could do tomorrow, he suggests, is to return something they've kept out of spite. One woman told Coleman that after reading about Ex-Spouse's Day last year she finally returned her ex-husband's favorite chair. She had held onto it for years, she told Coleman, because she didn't want her ex-husband to be comfortable.

"Then she realized that by keeping it she was hurting herself more than she was hurting him."

Coleman, who went through a divorce himself in 1970, says he doesn't really expect greeting card companies to start an Ex-Spouse's Day line. The card companies are apparently a little leery of new holidays. "They really failed on Grandparents' Day," he notes.

But Hallmark cards, which is located in Kansas City, did ask him to consult with them last year about their line of divorce cards. Coleman found the cards, for the most part, full of hostility and rage. "I wanted them to see the potential of a card less anger-oriented."

Coleman sells Ex-Spouse's Day Buttons (1-800-237-1922). One displays the Ex-Spouse's Day Logo (an X with a heart in the middle); a second button, he admits, is a bit more cynical. "I'm okay, you're history," it reads. "It's an attempt to say `I'm in charge of my life,' " he explains.

Coleman also sells Ex-Spouse of the Year buttons. This year he chose heavyweight boxing champ Mike Tyson and actress Robin Givens as the official Ex-Spouses of the Year. Although they seem to embody everything that Coleman is rallying against, that's the point, he says.

"Their short, turbulent marriage was obviously an unhappy union," he explains. "Now that the couple are divorced, each can begin the healing process that will hopefully lead to new, more loving relationships."

Coleman is already looking ahead to Ex-Spouse's Day, 1990. With the divorce rate hovering near 50 percent, there will certainly be no scarcity of celebrators, and he already has a celebrity couple in mind.

"I'm looking at Jane Fonda and Tom Hayden for next year."