Hello, firstly, please, please dont terminate this pregnancy unless you really really want to. You stated that your gut instict is to keep it. I think you should always go by this. Forget what other people think... I have learned this. Yes, they may talk about you for a week or so but pretty soon someone else will be gossiped about and you will be old news.
Regarding your family - yes - they may take it badly BUT more often than not, even in what may seem to be a bad situation, when the baby is born - alot will change. More often than not they will not not be able to love it.
I would be concerned that if you are suffering from depression and go through a termination because of what others may think/ say/ feel, and not because of what YOU want, it may have a terrible long term effect on you and you have to remember you will be no good for your daughter should this happen.
Regarding your age, I dont think you have cause for huge concern - my aunt had her third at 42 with no complications. I would however echo what everyone else has said and advise you go see your gp immediately.
About your partners age, how about looking at that as a positive as opposed to a negative? he is wiser, has life experience, maturer - all of which are definately plus' when becoming a father.
I really hope you are ok and dont make any rash decisions based on what others think.
I wish you and your children all the luck in the world.