Hi, and welcome..
It sounds as though you just threw this kitties together without a proper introduction. I used to do that too, and it works for some cats, but not most, to be honest with you..
You're going to have to start a re-introduction process - starting from scratch. Cats are very territorial and need to feel comfortable in their spaces. I recommend on putting Meeka in a room on her own, with her own litter box, food dish, etc. Gradually you can work it so that they are together again, but if you want them to be civil, it's going to take a long time.. I've been trying to introduce a former mother stray cat in with my other two, and it's a very slow process - so far it has taken several months..
Here's a website you might want to check out: http://www.catsinternational.org/art...roduction.html
And if you do a search for cat introduction on this forum, you'll find other ideas from others who have been trying to make it work.