Brave of you op to be open about your true feelings. Those posters who have commented that they could not imagine not taking in a child in these circumstances need to get real. If they are so altruistic, well there are plenty of fostering opportunities out there.
I have taken on not one, but two children of the family. The first was by agreement and an order of the court was made accordingly. The second was a "forced" situation upon the mother and we were initially reluctant to make further court applications. In fact, the sw actually rang the Judge to see if he could fit us in for an early application alongside our already ongoing hearings for the first child!
What sort of order would be in place op? We were approved, after months of work, with ss for Special Guardianship. However, we ended up with a residence order for the first (opposition from the father) and an agreement for Special Guardianship for the second. Very messy, distressing, emotional, stressful and very hard financially. We had to remortgage our home to meet the legal costs.
Ten years on, do I have any regrets? Well no, to be honest it has been a privilege but my circumstances were different. My girls were grown up more or less but I still found it incredibly hard. The second boy had issues and initially we suspected fetal alcohol syndrome. He is a beautiful, loving little boy but not without his difficulties.
The main issue for us was the father of the first child, who is a violent offender, who took us back to court continually demanding access, changes to access visits etc. Nightmare. However, this doesn't seem to apply in your case.
So many people believe you can just take on a child but you have to jump through so many hoops. Unless you have been there, you simply do not know.
I honestly think op you are spread too thin already. Any professional worker looking at your family would see a loving, decent family but one that perhaps could not give the required attention to a 2.5 year old. This is not a criticism but the truth.
I am in my fifties now, the boys are in their teens and it is full on.
There can be no criticism of you op. You are already providing care for the child involved and you already feel the weight of your responsibilities laying heavily upon you.
I am sorry I cant offer any answers for you here, but can only tell it from my perspective, but pm me if you feel I can assist you in any way.