Did I cause premature marionette lines from using a facial exercise device? If so, what can I do to diminish them?

Hello, thank you for your question. Fillers are typically a better choice to get around the mouth. An in-person consultation with a board-certified dermatologist would be needed to evaluate your concerns and come up with a custom treatment plan.

these lines just happen from aging -- lost volume and skin sagging -- not from facial devices. you will need fillers + energy devices like morpheus and thermage.  threads can also help at younger ages or even accutite. at home dermarolling helps keep the skin tight (see link to my weekly protocol at emeragecosmetics.com)
For facial rejuvenation, 
1) skin care with products and PRP/microneedling
2) PDT light therapy few times a month with growth factors
3) laser treatments like clear and brilliant regularly and a few times a year Fraxel/halo Viva, Co2/Erbium
4) Sculptra injections a few times a year for collagen production with fillers like juvederm/restylane/belotero/radiesse/bellafill
5) thermage/ultherapy for yearly skin tightening with or without PDO or cone based instalift threads for lifting
6) botox every 2-3 months to stop movement lines and prevent lines at rest
7) deep microneedling RF like Fractora/morpheus8 for tightening of the skin
8) Vascular laser like vbeam/excel V or BBL forever young treatment every quarter (3-4 months)
Best, Dr. Emer.

Marionette lines are improved nicely using filler.  The treatment is done in the office with no down time and the results last up to one year.  See an expert injector near you to learn more.