This makes no sense to go straight to surgery. Are you sure you are stating the situation correctly?
If you had an actual abcess infection they would have put you on IV antibiotics. You would be very sick, fever and possibly vomiting. An infection is very serious because if the infection escapes the abcess (which is actually a protective function of the body) and spread to the bloodstream and heart, you can die. You would likely have streaking at the area, which looks like your girlfriend took her nails to your skin and ripped your skin in a fashion away from the injection spot. First step they would lance the area, which is not surgery. This is usually a mild sedation and then they use a scalpel, slice and allow the area to drain. I have even seen times where they allow the wound to stay open for days, with gauze in it. I have even heard of crazier stories with abcesses where they pack it with maggots to allow the maggots to eat away the rotted flesh and bacteria, but that is much rarer.
Out of thousands of clients I have only ever seen a few AAS induced "abcesses" in 25+ years. Several of them were from INJ winstrol. In the hospital I saw tons of other abcesses, naturally occurring, spider bites, etc, etc.
So yes, gear can cause an abcess, especially if contaminated. Or even if the BA% is too high. Or in your case bc its T400.
Hard to believe you had bruising in 30mins sir. The only way this is possible is if this was actually a "hemotoma", which is different from an abcess. This has fresh bleeding internally and and does swell rapidly. It does cause pain and tenderness. Again a hemotoma, you can remove blood and puss and usually "draining" the area is all that is needed. That's "if" an oral antibiotic like BACTRIM is given alongside 800mgs of ibuprofen and that doesn't work.
No matter what the facts are here sir, the one fact is that T400 almost always has PIP and packs a nasty punch. In no way is it for an amateur, and in fact it's really not usually good for an expert. Regardless of how knowledgeable you are you still cannot always avoid an abcess or hematoma.
Toss the T400 and don't even go remotely near that injection site again sir for many many months as that area will be sensitive to inflammation, pre-abcess, etc, for a very long time tbh.
Good luck.