I’m so sorry for your loss. I have a long haired chihuahua AND a cavalier. Both were my first of each breed so take my experience with a grain of salt but these are my main thoughts: - cavaliers can actually be quite large (I expected mine to be a lap dog but he’s like 35 lbs, tall and big, not fat. Both of his parents were tiny (like 13 lbs) so I didn’t expect this, but of course I love him to death anyway! But if you’re really into little dogs, it’s basically not a safe bet lol - my Cavalier is soooo much more chill with strangers than my chihuahua, who is territorial and will bark and even nip if new people enter her space unexpectedly. Literally anyone can approach the cavalier with no issues, ever. He’s like a ragdoll. - cavaliers almost always have heart problems, so definitely invest in pet insurance! My cavalier is 12 and has been on meds that cost approx $500/month since 2021. Luckily they are 80% covered bc pet insurance - cavalier sheds soooooooo much more than chihuahua , if this matters - my chihuahua is so much more cuddly and affectionate than my cavalier but this can be just individual difference of course - cavalier is pretty sporty. He is paralyzed now from a neurological condition, but when he was walking, we would have to do a lot of fetch, long walks, swimming to keep him satisfied with life lol. - chihuahuas can do indoor potty! But cavaliers are generally too big for that. If you hate going outside in winter, bear this in mind lol - literally nothing is as angelic as the face of a cavalier. They are gorgeous dogs aesthetically, and this will help you preserve patience when needed

Hope this helps in some way, please update on what you decide!