Welcome! Sounds like you & I have about the same history - I had a shot mitral valve and damaged tricuspid, enlarged heart, fluid retention, etc. Was also in bad shape when diagnosed. AND I have 2 grandsons (6 & 3) and a girl due in August (I expect her in July, however). And I think those boys are the best ever.
Please read through the threads on this site; any questions that present themselves, ask away.
You'll be amazed at how different you feel after you've recovered from surgery. Recovery takes quite a while, but ever so slowly you start feeling like you should have all along.
I'm sure this is all a shock for you and your girls; the best thing is that you have a mechanical problem that can be corrected by a good mechanic. There are lots worse things . . .