Skip the balloons, it is an ugly and inappropriate thing to do.
Black balloons can only be sent by a very closed loved one. You are not that.
Sending them is not only mean and spiteful, it is invasive and intrusive, it is bordering on stalker like behavior.
You are not her spouse, not her significant other, not her friend, not her lover. Back off and leave her the he11 alone. Criminy.
If you really want to be the bigger person, encourage your kids to make something of their own choosing for her and support their project. If you feel you must give her a gift, give her movie passes for her and your kids (not you), or something like that -- a disposable gift certificate.
