Sounds like a difficult decision Binky, so many hugs to you.
I have had a termination, but in very different circumstances to yours. Uni student, no stability etc. I assume its much more difficult when you already have a family and can see the 'result' of the pregnancy, I know Ive found it hard dealing with a past termination since having DD, even though Im very pro choice and know I made the right choice.
When I got pregnant for the second time (all planned), I felt very regretful about the pregnancy (how it would effect our DD, comfortable life and finances, the whole coping issue of toddler and baby), then developed Hyperemesis, so went as far as looking up Tx clinics, but couldnt do it. So far Im 18 ish weeks and am now quite excited.
How many weeks are you? Do you have time to think about it for a few weeks as you sound unsure? Both options of a medical and surgical tx are quite straightforward procedures before 12 weeks I think.
Also keep in mind if you do sway on the side of keeping the pregnancy, a lot can change in 10 months, the 2.5 yr old may be in school or less clingy.
But if you do know you absolutely wont be able to cope, or simply do not want to continue, there is no shame in going for tx.
Comparing the Tx I had and this 2nd pregnancy: with the Tx I had, there was no doubt in my mind it was the right thing to do, I would have been devastated to have kept going with the pregnancy, and would have walked to the other end of the earth to get one. With this pregnancy, it was more worries, what about this or that issue etc, and no 100% in my mind, of 'this has to end now'.
I dont want to sway you either way, as either choice you make will be right for your family. Best of luck.