I'm going to give away my ex's tv
Why are you going to do that?
I feel like donating it to charity.
Well I think donating to charity is a noble cause, that TV is not yours and it belongs to your ex. Either you contact them and say if it's okay for them to donate the TV, or you can just donate something that belongs to you to donate to charity.
I'll give it to my brother, he has room for all my ex's stuff.
Well giving it to your brother is even worse. I think you should just contact your ex and let them know that you want them to take the TV. That way you'll get it out of the house and you won't have to worry about upsetting them.