@Subway11 - Well at least your father got to move back in with you. I bet that was nice. I would imagine that a legal marriage separation must be even more difficult than a divorce because with a divorce you have made up your mind to go separate ways, but with a legal separation you are separated but still legally married to the person.
At least with a divorce there is closure and you can start to rebuild your life, but with a legal separation you may build hopes of a reconciliation that may or may not come. I guess when there are kids involved this might make more sense than to go for a full blown divorce because some couples can work out their differences during counseling when they are apart from each other.
It gives them time to think about their feelings without getting into more fights. I think that when you are apart you also start to appreciate the other person more and that could really help rebuild the relationship.