Addressing envelopes

Originally I was going to get invites from this site but I just don’t like them a ton and Zazzle has great ones for less money. Problem is they don’t address them for you as the wedding sites do. They will print the return address on much nicer envelopes than here and the rsvp envelope just not the recipient on front of the invite envelope. So, my question is, does it look dumb or is it silly to purchase a pretty envelope with my return address already pre-printed in nice print on the back if I’m just gonna hand write the front of it with my sloppy writing? I’ve always been told that I have a really poor writing and to top it off I don’t have a job where I write anymore as I’m on the computer all day so it’s pretty bad. I do understand it’s proper etiquette and nicer to hand write things but if you’re going to spend all this money and time getting a really nice elegant invite why destroy it was sloppy handwriting, but I’m also aware people just throw these away so I’m not really sure what to do. What are other people doing.? I thought about trying to print them on my printer but I think it’s just going to destroy the envelope. I’m also wondering is it tacky for me not to have an inner envelope especially if the post office destroys the outside one in transit? I don’t really see that any of these sites are offering an inner envelope. I’m just wondering if that’s kind of gone by the wayside unless you’re ordering from a really nice company.