Although I wouldn't typically describe myself as having issues with anxiety/depression, I actually had quite a melt down yesterday. I found myself incredibly overwhelmed, anxious, and feeling really alone. I used to have some issues in the past, so I know (and can recognize in myself) that I tend to build up those feelings, and the more I think about them and the cause of them, the worse I feel, the worse I feel, the less capable I feel, and then I feel even worse! And that cycle continues. Many times that results in me just getting really angry (I'm a fire sign?) and dropping a bomb on DH on everything he isn't doing to help a situation that he doesn't know exists. Luckily he also recognizes this sequence of events, so he knows not to take it personally (most of the time). Yesterday, though I just brought DS into his room to nurse, and I just lost it and bawled my eyes out for about 15 minutes, which I never do. DS thought I was laughing. But I got a good cry out, and rested for a bit and it created that same release of the tension that was causing the emotion.
So, whatever you can do to release tension is what I would recommend - don't try to "hold it in". Yell, scream, cry, whatever. Don't beat yourself up because you are having the emotions and try to bottle them up, just honor them, release that tension, and move on if possible. I used to have issues with anxiety and depression when I was younger, and I had a lot of success with treating it with diet and exercise. My biggest trigger food is dairy, which is unfortunately something I have been craving like crazy since becoming pregnant (I must need a particular nutrient that I am not getting otherwise) so I have been toggling avoiding dairy (and other foods I generally avoid) because I feel like I *need* something from them, and avoiding them to keep myself sane. I think that this is why I am beginning to have more emotional issues this pregnancy - my meltdowns seem to coincide with when I am phasing out the trigger foods. (So, yes it is like having withdrawals).
If I were you, I would keep a food journal and see if there is a pattern to your anxiety. I would also look into the GAPS (Gut and Psychology Syndrome) diet, about how the health of your gut can influence your psychology. And remember to listen to your body and give it what it needs. Love, rest, and nourishment.