Electra, I think you have it there - it is truly a rock/hard -place scenario, and what you have to do is work out what you'll be left with each way. For me it took a few weeks to get there (I hate to do things without others' approval) and in the meantime I hadn't got a clue which path to take so I was hedging it.
But I knew if I had a termination there would be nothing, just possibly less work (babies are so much easier when you've done it before - as you'll know!) and less grief from other people (short term at least)
But if I didn't, and had the baby, I would have a baby at the end of it. That kind of swung it for me
Ramifications yes, some stress and a hard pregnancy (yours might be good, I had bad morning sickness) but then finally a good thing was born of it all. I don';t think I could have contemplated going through those awful few weeks at the start, only to end up with no baby - just too sad for words really. It would be hard either way but if you already have two reasonably happy children I think you have little to lose having another - as long as the baby would be Ok, cared for as you already do with your girls - then nobody can criticise your choice.
The father's involvement is a different matter - I'd find that much harder to deal with than a little baby. I didn't have too much hassle from my ex, as he didn't want a baby in the first place, but you might end up with access issues and so on, whether that would bother you I don't know...
anyway the people at Marie Stopes really put me off with their attitude, maybe I just interpreted it wrong but I felt rather horrid about the whole deal. I was pretty dumb to get pregnant by a nutter but it was my job (and wish) to deal with it, iyswim. And it's worked out fine