yes, I am still in touch with several, and they have grown up into lovely people.
The situations when I thought "I can take no more" were never related to the children. Mostly to the social workers - ( some were great) or once to one of the parents, who were horrendous to me and my children.
The government red tape - I ended up doing the most ridiculous things- like at one point having to "prove" a list of competencies that some one dreamt up for foster carers, like "proving" I could send an email, which meant sending an email to my boss, who then wrote a witness statement confirming he had received an email from me and I had sent it competently, etc
"proving" I fed the children veg, which meant making sure they always had veg they disliked on their plate, every meal time, so if the social worker called at a meal time, there was veg on their plate. Once the social worker called at meal time when I had served popular veg, and they had already eaten it, so it was recorded that she had witnessed their dinner plate, and there was no veg on it
This sort of thing used to have me pulling my hair out