Homemade Frosting- how long does it last?

Homemade Frosting- how long does it last?

I made some buttercream frosting a couple days before Christmas to decorate cookies. I was cleaning out my fridge today and found what was left of it- there is still a fair amount left, but I have no idea how to tell if it's still good. There isn't any visible mold, but around the edges of the frosting there seems to be a liquid substance. Do I just chuck it to be safe? The main ingredients are butter, powdered sugar, vanilla, and a little bit of milk. It's been refrigerated the whole time. I guess it's mostly the milk that concerns me.
WooHoo!

WooHoo!

Chinese Lantern vs Deadly Nightshade

Chinese Lantern vs Deadly Nightshade

Eggplants, photo and a question

Eggplants, photo and a question

Sick rosebush?

Sick rosebush?

Perenial Blue Flower identification.

Perenial Blue Flower identification.

More roses making an appearance and my first lilies of the year

More roses making an appearance and my first lilies of the year