I feel soooooo bad!

I had my baby girl back in November..a beautiful 8th month old right now. Wellll I found out I'm 8 weeks prego and I didn't get very happy about it and I'm still kind of unhappy about it. I guess because it's way too soon for me. But it happened and he/she is coming. I had so many complications with both my kids so I guess I'm nervous about doing it all over again. How do people normally stay sane with a newborn and a toddler? I'm sooooo nervous that I'll go insane lol. Any positive comments are welcomed and advice!