behaviour of my gelding

Question
Hi Lisa
I appoligise for the extremely long question, but i want you to have all the info so that you understand my situation!
I live in Cape Town, South Africa, and we have a small farm about an hour away that we spend most weekends on.
About two years ago I bought a highly strung saddler gelding for the farm. At the time I had one other gelding and three mares that were on our farm for a short while (as a favour to a friend). The group seemed to get on well, although my friends gelding was dominant over mine. Later my friend took his horses back and my gelding was left on his own. He became very friendly towards people, but I knew that he was lonely. When I first bought him i was told that he suffered from seperation anxiety, and it was evident in the fact that it was extremely difficult to ride him or even lead him away from other horses.
I recently adopted a rescue filly (almost 2ysr old) as a companion for my gelding. After being on his own for quite a few months he obviously was a bit jelouse of her, and gave her quite a bad beating. She was very weak and thin when i got her and couldnt protect herself at all.It was a very scary few days for me because whenever i went near them or even walked past them, he would turn on her and really hurt her quite badly. They have since become best friends, although my gelding seems to be quite jealous/protective over me and doesnt like the filly to spend too much time with me.
I recently found out that the filly is heavily pregnant (she must have been when i got her).The farm is a fruit farm and i have three large paddocks but they are all quite far away from eachother. I have divided the one in front of the house into two, and am keeping them seperate for the foals safety.
Since i have done this, although they are only seperated by a fence, my gelding seems to be aggressive towards the filly again. I make a point of going to him first and feeding him first, but he often gallops towards her with his ears back right until he gets to the divide.
Yesterday he managed to get into her side of the paddock and chased her very aggressively and took a big bite out of her rump! He olny stopped because their food arrived and he is very greedy.
I am very worried about how i am ever going to introduce him to the foal.I cant keep the two of them in the divided paddock because the grazing will run out, and i cant split them up into different paddocks because my gelding gets very distressed and hardly even grazes when seperate. I also fear that the more seperation i give them, the more he will retaliate when finally together with the filly and her new foal.
At one stage when i first introduced them and he started attaching her, i put him loose in the farm and kept her in the paddock- he went absolutely mental and galloped up and down the side of the paddock until he got a huge stick stuck in his frog. I pulled it out and he was limping so i had to put him back in with her (as i was scared he would injure himself further). When i put him back in his rage had muliplied and he chased her and bit her until he tired himself out- she was so weak and scared that she could no longer stand and had to sit down!
Im very scared that seperating them could bring back this kind of behaviour in him when they are finally put together.
Please can you give me any advice about this situation, and how to reintroduce them (even though they are only seperated by a fence)

Answer
Hi Skye,
          You have a two prong question here. Regarding putting the foal and mare back in with your gelding I would not do that until the foal is at least 4 months of age. Your bigger issue is that your gelding's behavior has gone from being a simple pecking order to a jealousy issue. In cases like this the safest thing is to keep the horses separated. If you can put one in the paddock and let the other one go around the farm then that would be great. You could also keep them in separate paddocks. See if you can borrow an Alpha mare to put in with your gelding and after she teaches him some manners you could try to reintroduce the filly. There is a good chance that when she is gone then you would still have to keep them separate.

Lisa