Magick won't dial 911 for you if this person ever decided to commit suicide. You need to play your part. Empathy, sympathy, understanding , and be a steadfast bridge. If they chose to turn to you as walk on that bridge, don't let it fall and fail them. You will want to walk in their shoes aswell; figure out why they are depressed. Try to place a bandage over their wound.
This person should be seeing a doctor. If you can't get this person to go to a doctor, don't deceive them to get them into an office. It's their choice, not yours. If they do stray away from receiving medical assistance, keep your eyes close on them. As a matter of fact, always stay watchful, and keep the Suicide Helpline number, depending on your location, near you or stored on your phone. After you've assured yourself you will do this, I say it will be safe to use magick that will only help the depressed loved one, and not hurt or harm him/her, or anyone else.
I'd recommend a Banishing spell, to ward away any evil and negative energy. Negative energy can block the chakras and suppress our normal humanity, and this could be the case of the depression. Spirits can bring these negative energies, and actually are more common than you think. Try this:
You can substitute Bay Leaves with dried apple slices since they aren't as accessible as other herbs in dire situations. If you've no access to myrh, nutmeg would work fine. Use a candle in this, and nearly arranged the herbs around the candle, on an altar or clean table. Burn the nutmeg and other herbs, except the dried apple if you chose so to use. Keep water nearby. Wear an amulet for extra strength, and mayhaps you meditate and draw energy from any sphere of the day, such as dusk, dawn, or midnight. Let the candle burn on its own after you close the spell with an end chant such as "so more it be".
If you need any more information or help, feel free to message me or any moderators. I hope it all goes well to you.
~May the Visions of Isis guide you