Hi Antony! I think it all depends on what you want or need to do with your language skills. If you are satisfied with your current Spanish level and don't need to improve it further, then you can resume learning Italian. Of course, as you already know, learning two languages that are close to each other can be hard because you can easily mix them up.
Learning two languages at the same time is certainly doable, but I think the more unrelated with one another, the better. Spanish and Italian at the same time can be a more difficult pair, but not an impossible one!
Let me know if I can help you with Italian,
Michele