Hi Sam
So, I know that heavy heart, and the drag it is to maintain appearances. That sucks. Here, let me give you a virtual hug. You're not alone with this. I hope there are people in your life who can give you a more tangible sense of fellowship and friendship. It can be very lonely, that place you describe.
Ultimately, these things - energy changes, love - will arise almost as side-effects of
letting go (a.k.a unbinding, liberation, vimutti, etc). Since letting go is not an action but cessation (nirodha, as in the third noble truth) of action, this "letting go" is more of a description than practical advice, so not really directly useful.
Since this is the DhO, here's some practical advice, which may or may not be helpful: in meditation, observe the sadness/pain/suffering. You're in a safe place when you meditate, so it's ok to find out how this feels, how and where it moves, how the rest of the body feels as this happens (maintaining or returning to awareness of the entire body helps to avoid contracting too much around the sadness). That's very strong practice! If you use noting technique, hold the notes lightly and listen into the pain before "firing" that note. That way, it's more of a kind of surrender practice, or a way to consent with whatever arises, and the notes can be used to express the surrender or consent. If you like, you can research the Christian "Centering Prayer" technique (which is really noting with a surrender/devotion angle to it).
If you can get into some tranquil states now and then, to rest yourself from the hard work of investigating suffering, that's a bonus. Also, walking meditation, in the form of a stroll through the park or along a river, can have good effects on heavy-heartedness (it's been useful to me, so I keep recommending it).
As to being love: as always, start with what's closest at hand, yourself. Be nice and gentle with yourself, and all else will, if not follow, at least be a lot easier.
Judging other people: if you notice yourself doing it, don't beat up on yourself, but again, be gentle and nice with yourself. If you like, you can ask yourself, "what can that person teach me?" There's a saying by Ram Dass which goes like this: "if you think you're so enlightened, go spend a week with your parents." Finding out about the buttons people are pushing in myself is a major source of insight for me.
That was a lot of advice. Use what you like, disregard what you don't, there are no obligations attached

Remember: be gentle with yourself, especially when you're hurting. Here, have another hug!
Cheers,
Florian