Am I wrong to feel like this isnt the right thing for us?

Ok so my fiance is 25 and Im 24. We've been together 5 years. We have been long distance for the last 4 years due to me needing to go to university across the country. We both graduated with professional degrees last year though and I'm just finishing up my internship. I'll finish my internship next week and then move to the same city as my fiance to start my residency. We're getting married in December.

My fiance comes from a pretty sad background. His biological parents regained custody of 3 of his younger siblings 6 years ago. Well because of that my boyfriend reestablished contact with his bio-parents (he always maintained contact with his siblings even though they were in seperate foster homes) and they're absolute chaos. I won't go into all their issues and the problems they cause us. But, basically my boyfriend has been supporting his family for the sake of his siblings. Things aren't great though for them. The 10 year old has severe learning disabilities and possible delayed mental development. The 13 year old is a sweet and smart kid, but she's having a lot of social issues that are a bit more than your average teenaged stuff. Then 16 year old is very likely involved with drugs through her 28 year old boyfriend and that relationship is a total mess.

Well, my boyfriend wants them out of his parents house. He brought up the idea of potentially having them move in with us once we're married. We won't be moving in together until we're married and he's said he knows he can't do this on his own. Finacially we'd be fine as my boyfriend has been supporting them already. In fact it'd be cheaper since he wouldn't be paying for his parents anymore. But, I just think it'd be a massive responsibility we're not ready for. And my boyfriend isn't even sure this is a good idea at all either. He just mentioned it and wanted to see what I thought. Unless we both think it's a good idea and are absolutely sure about this, we won't do it and will look for another solution.

I mean we will be moving in together for the first time and adjusting to a married life. I'll be 6 months into a 4 year residency program- I won't really be around much due to studying, classes, work and being on call. When I am able to be around I want to focus on our marriage. And these kids aren't just kids, they're kids with a lot of serious issues that need serious attention and help. I just don't think I'm able to or ready to give that kind of help. I'm not even ready to have my own baby that only has basic and normal baby needs. It terrifies me just to think about having to deal with a child that needs professional help, a teenager who will need so much support getting through school (I remember my mum spending hours with me every day when I struggled socially!) and a teenager that might need rehab. And the fact that she might have a drug problem puts me in a thought spot as I have access to prescription drugs and when on-call I often have drugs with me at home. All drugs are locked up securely and I never let the keys out of my sight. I'd end up having to leave all that at the hospital and then drive there.to pick things up which slows me down in emergency situations. Its not ideal, but I could manage. But I'd still worry she'd get my script pad or something. And the boyfriend scares me too. Even though we'd take her across the country, I still worry he'd come after her. He's got a criminal record for assualt and that just terrifies me too, especially if she wants to be 'rescued' from us.

I just don't know where to even start with these kids! And I don't think I can be any kind of mother figure to them with my career which I don't want to give up (if I give up this residency spot I may never get another chance at this tecahing hospital and it's the best in the country and in the right city to be with my fiance). Even if I stayed home I don't think I'd have the skills and ability to handle these kids. I'm not ready to be a mum in any sense let alone like this. It just feels too like way too much. There are other options for his siblings and I do want to help them, but in a way that I can. Nothing in my life ever prepared me for anything like this- until I met my fiance I had never come close to things like this in such a personal way.

But, I feel like I should be ready for this because they're going to be my family. I should be able to give them more than they have right now. Maybe it's because I was always taught to take in my baby brothers if something happened to my parents, but my brother's have never had any kind of issues like this. Taking them in would be hard, but not like this. But, I still feel like I should be able to do the same for my fiances siblings. But then I think it'd be better to find a solution where they'd get more experienced and professional help that could help them more than I could. I don't want to cast them off, but I think I'd just make things worse because I cant be what they need.

My fiance has a lot of similar concerns too by the way. He's an amazing brother who's tried so much to help them already and he's had some success (there's an older sister that he helped get out of a very bad situation a few years ago and she's now in school and working a good job and in a healthy relationship which is amazing). But, even then this is huge and we're both just so lost.