I need advice or some nice words

we just got news that my boyfriends sisters heart is failing quite quickly, she has a 7 year old son and shes a single mom.

She has no choice but to leave her son to my boyfriend in her will, resulting in us taking him in.

We are 20 and 22 years old, both work full time and have a puppy who will be 1 year old in august, dosent get along with kids, and scares a lot of adults.

Has anyone experienced this sort of thing before?

or give me insight on this type of situation and what to expect..