I think your DC ideas show a lack of developed thinking about fostering.
It is a long process to get approved. If they get beyond the initial stages, there will be lots of in-depth discussions which include talking about their relationship with you and your experiences of fostering. The difference between a foster child (who is usually temporary in the household, even if fairly long term) and their own child will be covered. They will be given a lot to think about and they will have to show a mature understanding and ability to understand boundaries and what is appropriate.
Your DC sound like they have a very limited understanding of fostering and if empathy. It is surprising they reacted to your feelings as they did, when no doubt they have heard before how difficult you find your past. In itself, these responses make me think they might well not get far with the fostering process.
Is there any chance that this is really about creating conflict with you?
I wouldn’t worry too much at this stage. Them having this idea and it becoming reality is a huge gap. It is fairly unlikely to happen and if it does it would be a long time diwn the line and could only be after a long process and training where they would need to adjust a lot of their ideas. One of the training areas is about wider families and impact and in all liklihood, social workers would want to speak with you along the way.
many posters on this thread are very simplistic about this. Fostering isn’t a snap decision and it’s not just about doing a ‘kind thing’ for some children. It is hugely complex and even moreso when you have your own children.
I can see why them saying this has been upsetting for you. Possibly by biting and responding to their comments (which no doubt wasn’t actually a surprise to them) you aren’t helping. Quite likely saying very little about it and just commenting about what a long process it is, would be better and not provoke the reaction. They may well not be very serious. It may well it be fully thought out. Many many people lossless consider it and after a very quick look into it decide not to go further. Many others decide not to proceed or the process shows them up as not really suitable at any stage of the process. I probably wouldn’t mention this to them, but let them look into it if they want to. It is a long road and their levels of maturity and suitability sound doubtful, but it is difficult to tell from here.
At the same time, perhaps it would be good as a separate thing to consider your own feelings about the past and look into some kind of support in dealing with that.