Hello and thank you for the great question. Both CBD and THC are safe to use with SSRIs and SNRIs.
However, keep in mind that cannabis is best used at the lowest dose and frequency possible to address your depression. There is both scientific and a plethora of adecdotal evidence that heavy cannabis use can lead to the worsening of depression.
In one 2014 study, researchers found that the brain’s of chronic cannabis consumers became less sensitive to dopamine over time. Dopamine is a neurotransmitter that promotes pleasure, reward, pain, and focus. Lack of dopamine is also implicated in some models of depression. http://www.pnas.org/content/111/30/E3149
The idea here is that less sensitivity to dopamine makes you apathetic and detached, two major symptoms of depression.
Other animal research has found that THC in low doses boosts serotonin, but high doses of the cannabinoid had the opposite effect. http://www.jneurosci.org/content/27/43/11700