Oriel, I do not believe in the reality of black magic. However, I am very aware that some people do believe in it, whether they think they practice it, or think that or are affected by it; and that in this way, "magic" can affect their feelings. Even without reading your chart, I can suggest that your former "friend" was dabbling in some unsavoury practices, that he is maliciously gossiping about you behind your back. Such a situation would make many people feel anxious and uneasy!
If we take your ruler as the moon (1st house); and secret enemies as well as "dark magic" as ruled by Mercury (12th house) we can look and see how they interact. The moon is applying to a conjunction with Mercury (in the 8th house), so your concerns that your "friend" is behaving badly towards you are correct. We also see the ruler of the 6th house (Jupiter) in the 12th house, which is another indication that he is up to no good-- although there are some other similar indicators that I do not see in your chart.
Let's just assume that this man hopes to harm you in some way, perhaps by turning your friends against you. If you think he is likely to damage your reputation or harm you in some real way, see what steps you can take to warn your friends that this is what he is doing.
On a more metaphysical level, this man cannot "psychically attack" you without your permission. If he can frighten you, such that you start to feel "heavy", &c., then you have given him permission to upset you-- which is probably exactly what he wants, after you snubbed him. You are far stronger than his pathetic efforts, so please don't give in to the types of fears that he is hoping you will feel. Don't do his dirty work for him.
I note that the sun (in Jupiter's sign) is leaving the 8th house and applying to a trine with Jupiter as it enters the 9th house. The 9th house and Jupiter deal with faith, philosophy, and religion. If you believe in a kind and loving God, however you understand Him, this faith is far stronger than any make-believe black magic or charms against it. If you don't believe in the God of the Bible, you can trust and have faith in a beneficial divine consciousness to support you through this upsetting incident.
You are stronger than you know.